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1.  The Association between Dry Eye Disease and Physical Activity as well as Sedentary Behavior: Results from the Osaka Study 
Journal of Ophthalmology  2014;2014:943786.
Purpose. To assess the association of dry eye disease (DED) with physical activity and sedentary behavior. Methods. The cross-sectional survey conducted included Japanese office workers who use visual display terminals (n = 672). DED was assessed according to the Japanese Dry Eye Diagnostic Criteria, and participants were categorized into “definite DED,” “probable DED,” or “non-DED” groups based on the results of DED examinations. Physical activity and sedentary behavior of participants were assessed using the International Physical Activity Questionnaire (IPAQ), and physical activity level was calculated in metabolic equivalent units per week (MET, min/week). Participants were classified as having a high, moderate, or low level of physical activity. Results. Participants with abnormal tear break-up time (BUT) (≤5 s) were involved in sedentary behavior for significantly longer duration than those with normal BUT (P = 0.035). Non-DED participants (14.5%) tended to have higher levels of physical activity than definite DED participants (2.5%). Participants with definite DED had significantly lower MET scores than those with non-DED (P = 0.025). Conclusions. Our findings suggest that a lower level of physical activity and sedentary behavior are associated with DED; however, longitudinal/intervention studies with large groups of participants are needed to validate these findings.
doi:10.1155/2014/943786
PMCID: PMC4248401  PMID: 25485144
2.  Crystallization and preliminary X-ray crystallographic analysis of Pz peptidase B from Geobacillus collagenovorans MO-1 
In this work, Pz peptidase B, an intracellular M3 metallopeptidase that is found in the thermophile Geobacillus collagenovorans MO-1, was crystallized using the counter-diffusion method.
Pz peptidase B is an intracellular M3 metallopeptidase that is found together with Pz peptidase A in the thermophile Geobacillus collagenovorans MO-1 and recognizes collagen-specific tripeptide units (-Gly-Pro-X-). These peptidases have low homology in their primary structures; however, their cleavage patterns towards peptide substrates are similar. In this work, Pz peptidase B was crystallized using the counter-diffusion method. Data were collected to a resolution of 1.6 Å at 100 K from a crystal obtained in the Japanese Experiment Module (JEM; also known as ‘Kibo’) at the International Space Station (ISS). The crystal belonged to the trigonal space group P3121, with unit-cell parameters a = b = 87.64, c = 210.5 Å. A complete data set was also obtained from crystals of selenomethionine-substituted protein.
doi:10.1107/S1744309112018969
PMCID: PMC3388914  PMID: 22750857
Pz peptidase B; Geobacillus collagenovorans MO-1; microgravity
3.  Frequent amplification of ORAOV1 gene in esophageal squamous cell cancer promotes an aggressive phenotype via proline metabolism and ROS production 
Oncotarget  2013;5(10):2962-2973.
Chromosomal band 11q13 seems to be one of the most frequently amplified lesions in human cancer, including esophageal squamous cell cancer (ESCC). The oral cancer overexpressed 1 (ORAOV1) gene has been identified within this region, but its detailed biological function in human ESCC remains largely unclear. In our clinical samples of stage III ESCC, ORAOV1 amplification was observed in 49 of 94 cases (53%). ORAOV1 amplification was significantly associated with a poorly differentiated histology and tumors located in the upper or middle esophagus. Patients with ORAOV1 amplification tended to have a shorter survival period, although the difference was not significant. To investigate the function of ORAOV1, we created ORAOV1-overexpressed ESCC cell lines that exhibited increased cellular proliferation and colony formation, compared with in vitro controls. In vivo, ORAOV1-overexpressed cells exhibited a significantly increased tumorigenicity and a significantly larger tumor volume and poorer differentiation than controls. The peptide mass fingerprinting technique demonstrated that ORAOV1 bound to pyrroline-5-carboxylate reductase (PYCR), which is associated with proline metabolism and reactive oxygen species (ROS) production. Then, ORAOV1-overexpressed cell lines were resistant to stress treatment, which was cancelled by PYCR-knockdown. In addition, the ORAOV1-overexpressed cell line had a higher intracellular proline concentration and a lower ROS level. Our findings indicate that the ORAOV1 gene is frequently amplified in ESCC, enhances tumorigenicity and tumor growth, and is associated with a poorly differentiated tumor histology via proline metabolism and ROS production. ORAOV1 could be a novel target for the treatment of ESCC.
PMCID: PMC4102783  PMID: 24930674
oral cancer overexpressed 1; esophageal squamous cell cancer; pyrroline-5-carboxylate reductase; proline metabolism; reactive oxygen species
4.  Pancreaticoduodenectomy following total gastrectomy: A case report and literature review 
We present a case of afferent loop syndrome (ALS) occurring after pancreaticoduodenectomy (PD) in a patient who had previously undergone total gastrectomy (TG), and review the English-language literature concerning reconstruction procedures following PD in patients who had undergone TG. The patient was a 69-year-old man who had undergone TG reconstruction by a Roux-en-Y method at age 58 years. The patient underwent PD for pancreas head adenocarcinoma. A jejunal limb previously made at the prior TG was used for pancreaticojejunostomy and hepaticojejunostomy. Despite normal patency of the hepaticojejunostomy, he suffered from repeated postoperative cholangitis which was brought on by ALS due to shortness of the jejunal limb (15 cm in length). We therefore performed receliotomy in which the hepaticojejunostomy was disconnected and reconstructed using a new Y limb 40-cm in length constructed in a double Roux-en-Y fashion. The refractory cholangitis resolved immediately after the receliotomy and did not recur. Review of the literature revealed the lack of any current consensus for a standard procedure for reconstruction following PD in patients who had previously undergone TG. This issue warrants further attention, particularly given the expected future increase in the number of PDs in patients with a history of gastric cancer.
doi:10.3748/wjg.v20.i10.2721
PMCID: PMC3949282  PMID: 24627609
Pancreaticoduodenectomy following total gastrectomy; Afferent loop syndrome after pancreaticoduodenectomy
5.  The Transcription Factors Atf1 and Pcr1 Are Essential for Transcriptional Induction of the Extracellular Maltase Agl1 in Fission Yeast 
PLoS ONE  2013;8(11):e80572.
The fission yeast Schizosaccharomyces pombe secretes the extracellular maltase Agl1, which hydrolyzes maltose into glucose, thereby utilizing maltose as a carbon source. Whether other maltases contribute to efficient utilization of maltose and how Agl1 expression is regulated in response to switching of carbon sources are unknown. In this study, we show that three other possible maltases and the maltose transporter Sut1 are not required for efficient utilization of maltose. Transcription of agl1 was induced when the carbon source was changed from glucose to maltose. This was dependent on Atf1 and Pcr1, which are highly conserved transcription factors that regulate stress-responsive genes in various stress conditions. Atf1 and Pcr1 generally bind the TGACGT motif as a heterodimer. The agl1 gene lacks the exact motif, but has many degenerate TGACGT motifs in its promoter and coding region. When the carbon source was switched from glucose to maltose, Atf1 and Pcr1 associated with the promoters and coding regions of agl1, fbp1, and gpx1, indicating that the Atf1-Pcr1 heteromer binds a variety of regions in its target genes to induce their transcription. In addition, the association of Mediator with these genes was dependent on Atf1 and Pcr1. These data indicate that Atf1 and Pcr1 induce the transcription of agl1, which allows efficient utilization of extracellular maltose.
doi:10.1371/journal.pone.0080572
PMCID: PMC3818258  PMID: 24224056
6.  Spt6 
Epigenetics  2013;8(12):1249-1253.
As posttranslational modifications of histones H3 and H4 determine the state of chromatin in cis, these histones should remain attached to template DNA during transcription in order to maintain the state of chromatin. RNA polymerase II itself can transcribe the nucleosome template without changing nucleosome positioning. However, it was uncertain whether Spt6, a highly conserved polymerase-associated histone chaperone, prevents “preexisting” histone molecules from being dissociated from template DNA during transcription. We recently showed that Spt6 prevents transcription-coupled loss of posttranslationally modified histone H3. Taking previous studies into account, we would like to propose here that Spt6 has two fundamentally distinct functions in the regulation of histone modification: one is to act as a platform for histone modifiers and the other is to act as a molecular liaison between histone molecules and template DNA to prevent cotranscriptional dissociation of preexisting histones in order to maintain locus-specific modifications.
doi:10.4161/epi.26487
PMCID: PMC3933485  PMID: 24107707
Spt6; epigenetics; RNA polymerase II; posttranslational modifications; histone methylation
7.  Mediator Directs Co-transcriptional Heterochromatin Assembly by RNA Interference-Dependent and -Independent Pathways 
PLoS Genetics  2013;9(8):e1003677.
Heterochromatin at the pericentromeric repeats in fission yeast is assembled and spread by an RNAi-dependent mechanism, which is coupled with the transcription of non-coding RNA from the repeats by RNA polymerase II. In addition, Rrp6, a component of the nuclear exosome, also contributes to heterochromatin assembly and is coupled with non-coding RNA transcription. The multi-subunit complex Mediator, which directs initiation of RNA polymerase II-dependent transcription, has recently been suggested to function after initiation in processes such as elongation of transcription and splicing. However, the role of Mediator in the regulation of chromatin structure is not well understood. We investigated the role of Mediator in pericentromeric heterochromatin formation and found that deletion of specific subunits of the head domain of Mediator compromised heterochromatin structure. The Mediator head domain was required for Rrp6-dependent heterochromatin nucleation at the pericentromere and for RNAi-dependent spreading of heterochromatin into the neighboring region. In the latter process, Mediator appeared to contribute to efficient processing of siRNA from transcribed non-coding RNA, which was required for efficient spreading of heterochromatin. Furthermore, the head domain directed efficient transcription in heterochromatin. These results reveal a pivotal role for Mediator in multiple steps of transcription-coupled formation of pericentromeric heterochromatin. This observation further extends the role of Mediator to co-transcriptional chromatin regulation.
Author Summary
DNA is packaged into chromatin structure, which is important for various genome functions such as gene expression and maintenance of genetic information. Heterochromatin is a condensed chromatin structure and involved in epigenetic regulation of gene expression through repression of transcription. Heterochromatin at the pericentromeric repeats in fission yeast is assembled by two distinct mechanisms, RNAi-dependent and Rrp6, a component of the nuclear exosome, -dependent mechanisms. In addition, heterochromatin spreads into neighboring regions in an RNAi-dependent manner. Both mechanisms are coupled with the transcription from the target loci by RNA polymerase II, but the molecular nature of the coupling is not understood. Here we showed that the multi-subunit complex Mediator, which directs initiation of RNA polymerase II-dependent transcription, functions in the coupling between transcription and heterochromatin assembly. Mediator is required for Rrp6-dependent heterochromatin assembly and contributes to the RNAi-dependent spreading of heterochromatin via enhancement of production of siRNA by RNAi machinery. These observations highlight the multi-functions of Mediator in the transcription-coupled processes.
doi:10.1371/journal.pgen.1003677
PMCID: PMC3744440  PMID: 23966866
8.  Overexpression of heparan sulfate 6-O-sulfotransferase-2 in colorectal cancer 
Molecular and Clinical Oncology  2013;1(5):845-850.
The heparan sulfate sulfotransferase gene family catalyzes the transfer of sulfate groups to heparan sulfate and regulates various growth factor-receptor signaling pathways. However, the involvement of this gene family in cancer biology has not been elucidated. It was demonstrated that the heparan sulfate D-glucosaminyl 6-O-sulfotransferase-2 (HS6ST2) gene is overexpressed in colorectal cancer (CRC) and its clinical significance in patients with CRC was investigated. The mRNA levels of HS6ST2 in clinical CRC samples and various cancer cell lines were assessed using a microarray analysis and quantitative RT-PCR, respectively. An immunohistochemical (IHC) analysis of the HS6ST2 protein was performed using 102 surgical specimens of CRC. The correlations between the HS6ST2 expression status and clinicopathological characteristics were then evaluated. HS6ST2 mRNA was significantly overexpressed by 37-fold in CRC samples compared to paired colonic mucosa. High levels of HS6ST2 mRNA expression were also observed in colorectal, esophageal and lung cancer cell lines. The IHC analysis demonstrated that HS6ST2 was expressed in the cytoplasmic region of CRC cells, but not in normal colonic mucosal cells. Positive staining for HS6ST2 was detected in 40 patients (39.2%). There was no significant association between the clinicopathological characteristics and HS6ST2 expression. However, positive staining for HS6ST2 was associated with a poor survival (P=0.074, log-rank test). In conclusion, HS6ST2 was found to be overexpressed in CRC and its expression tended to be a poor prognostic factor, although the correlation was not significant. These findings indicate that HS6ST2 may be a novel cancer-related marker that may provide insight into the glycobiology of CRC.
doi:10.3892/mco.2013.151
PMCID: PMC3915281  PMID: 24649258
heparan sulfate 6-O-sulfotransferase-2; heparan sulfate; colorectal cancer
9.  Spt6 prevents transcription-coupled loss of posttranslationally modified histone H3 
Scientific Reports  2013;3:2186.
The tail of histone H3 is an ideal medium for storing epigenetic information because displacement of histone H3 is heavily restricted during transcription. To maintain the locus-specific modifications of histone H3, histone molecules should be retained locally at the original position through multiple rounds of transcription. Here, we found that fission yeast Spt6, a highly conserved RNA polymerase II-interacting histone H3–H4 chaperone, is essential for the maintenance of Lys-4 and Lys-9 methylation of histone H3 in euchromatin and heterochromatin, respectively. In euchromatin, loss of Lys-4 methylated histone H3 and deposition of newly synthesized Lys-56 acetylated histone H3 induced by Spt6 inactivation were coupled with transcription. While in heterochromatin, Spt6 prevents histone turnover and cryptic transcription in parallel with Clr3 histone deacetylase. We propose that Spt6 retains posttranslationally modified histone H3 during transcription to maintain epigenome integrity.
doi:10.1038/srep02186
PMCID: PMC3711048  PMID: 23851719
10.  Gene amplification of EGFR, HER2, FGFR2 and MET in esophageal squamous cell carcinoma 
International Journal of Oncology  2013;42(4):1151-1158.
Molecular targeted therapy is expected to be a promising therapeutic approach for the treatment of esophageal squamous cell carcinoma (ESCC); however, the gene amplification status of molecular targeted genes in ESCC remains largely unclear. The gene amplification of EGFR, HER2, FGFR2 and MET was examined using a real-time PCR-based copy number assay of 245 ESCC surgical specimens of formalin-fixed, paraffin-embedded samples. Fluorescence in situ hybridization (FISH) and comparative genomic hybridization analyses verified the results of the copy number assay. EGFR mutation was detected using the Scorpions-ARMS method. The EGFR status and drug sensitivity to an EGFR tyrosine kinase inhibitor was then evaluated in vitro. Gene amplification of EGFR and HER2 was observed in 7% (16/244) and 11% (27/245) of the ESCC specimens. A multivariate analysis revealed that HER2 amplification was a significant predictor of a poor prognosis in patients with stage III post-operative ESCC. The L861Q type of EGFR mutation with hypersensitivity to EGFR tyrosine kinase inhibitor was found in one of the eight ESCC cell lines and one del745 type of EGFR mutation was identified in 107 clinical samples. In addition, we demonstrated for the first time that FGFR2 amplification was observed in 4% (8/196) of the ESCC specimens. MET amplification was observed in 1% (2/196). In conclusion, the frequent gene amplification of EGFR, HER2 and FGFR2 and the presence of active EGFR mutations were observed in ESCC specimens. Our results strongly encourage the development of molecular targeted therapy for ESCC.
doi:10.3892/ijo.2013.1830
PMCID: PMC3622677  PMID: 23426935
EGFR; HER2; FGFR2; MET; esophageal squamous cell carcinoma
11.  Complete Genome Sequence of Lactococcus lactis IO-1, a Lactic Acid Bacterium That Utilizes Xylose and Produces High Levels of l-Lactic Acid 
Journal of Bacteriology  2012;194(8):2102-2103.
We report the complete genome sequence of Lactococcus lactis IO-1 (= JCM7638). It is a nondairy lactic acid bacterium, produces nisin Z, ferments xylose, and produces predominantly l-lactic acid at high xylose concentrations. From ortholog analysis with other five L. lactis strains, IO-1 was identified as L. lactis subsp. lactis.
doi:10.1128/JB.00074-12
PMCID: PMC3318493  PMID: 22461545
12.  New insights into the binding mode of coenzymes: structure of Thermus thermophilus Δ1-pyrroline-5-carboxylate dehydrogenase complexed with NADP+  
A crystal structure of NADP+-bound T. thermophilus Δ1-pyrroline-5-carboxylate dehydrogenase refined to 1.55 Å resolution is reported. The structure provides structural insights into the mechanism of preference for coenzymes and enzyme activity.
Δ1-Pyrroline-5-carboxylate dehydrogenase (P5CDh) is known to preferentially use NAD+ as a coenzyme. The k cat value of Thermus thermophilus P5CDh (TtP5CDh) is four times lower for NADP+ than for NAD+. The crystal structure of NADP+-bound TtP5CDh was solved in order to study the structure–activity relationships for the coenzymes. The binding mode of NADP+ is essentially identical to that in the previously solved NAD+-bound form, except for the regions around the additional 2′-phosphate group of NADP+. The coenzyme-binding site can only accommodate this group by the rotation of a glutamate residue and subtle shifts in the main chain. The 2′-phosphate of NADP+ increases the number of hydrogen bonds between TtP5CDh and NADP+ compared with that between TtP5CDh and NAD+. Furthermore, the phosphate of the bound NADP+ would restrict the ‘bending’ of the coenzyme because of steric hindrance. Such bending is important for dissociation of the coenzymes. These results provide a plausible explanation of the lower turnover rate of NADP+ compared with NAD+.
doi:10.1107/S1744309107021422
PMCID: PMC2335078  PMID: 17554163
Δ1-pyrroline-5-carboxylate dehydrogenase; coenzyme binding mode; NAD(H); NADP(H); proline metabolic pathway
13.  Crystallization and preliminary X-ray crystallographic studies of Pz peptidase A from Geobacillus collagenovorans MO-1 
Pz peptidase A has been cocrystallized with a phosphine peptide inhibitor (PPI) that selectively inhibits thimet oligopeptidase and neurolysin.
Pz peptidase A is an intracellular M3 metallopeptidase found in the thermophile Geobacillus collagenovorans MO-1 that recognizes collagen-specific tripeptide units (Gly-Pro-Xaa). Pz peptidase A shares common reactions with mammalian thimet oligopeptidase (TOP) and neurolysin, but has extremely low primary sequence identity to these enzymes. In this work, Pz peptidase A was cocrystallized with a phosphine peptide inhibitor (PPI) that selectively inhibits TOP and neurolysin. The crystals belong to space group P21, with unit-cell parameters a = 56.38, b = 194.15, c = 59.93 Å, β = 106.22°. This is the first crystallographic study of an M3 family peptidase–PPI complex.
doi:10.1107/S174430910700334X
PMCID: PMC2330125  PMID: 17277461
Pz peptidase A; M3 metallopeptidases; collagen degradation; Geobacillus collangenovorans MO-1
14.  Overexpression, purification, crystallization and preliminary X-ray cystallographic studies of a proline-specific aminopeptidase from Aneurinibacillus sp. strain AM-1 
Preliminary X-ray crystallographic study of a proline-specific aminopepitdase from Aneurinibacillus sp, strain AM-1 was carried out.
To elucidate the structure and molecular mechanism of a characteristic proline-specific aminopeptidase produced by the thermophile Aneurinibacillus sp. strain AM-1, its gene was cloned and the recombinant protein was overexpressed in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected to 1.8 Å resolution from the recombinant aminopeptidase crystal. The crystals belong to the orthorhombic space group P21212, with unit-cell parameters a = 93.62, b = 68.20, c = 76.84 Å. A complete data set was also obtained from crystals of SeMet-substituted aminopeptidase. Data in the resolution range 20–2.1 Å from the MAD data set from the SeMet-substituted crystal were used for phase determination.
doi:10.1107/S1744309106047543
PMCID: PMC2225360  PMID: 17142913
proline-specific aminopeptidase; Aneurinibacillus sp. strain AM-1; thermophiles
15.  Reassessment of the In Vivo Functions of DNA Polymerase I and RNase H in Bacterial Cell Growth▿ † 
Journal of Bacteriology  2007;189(23):8575-8583.
A major factor in removing RNA primers during the processing of Okazaki fragments is DNA polymerase I (Pol I). Pol I is thought to remove the RNA primers and to fill the resulting gaps simultaneously. RNase H, encoded by rnh genes, is another factor in removing the RNA primers, and there is disagreement with respect to the essentiality of both the polA and rnh genes. In a previous study, we looked for the synthetic lethality of paralogs in Bacillus subtilis and detected several essential doublet paralogs, including the polA ypcP pair. YpcP consists of only the 5′-3′ exonuclease domain. In the current study, we first confirmed that the polA genes of both Escherichia coli and B. subtilis could be completely deleted. We found that the 5′-3′ exonuclease activity encoded by either polA or ypcP xni was required for the growth of B. subtilis and E. coli. Also, the 5′-3′ exonuclease activity of Pol I was indispensable in the cyanobacterium Synechococcus elongatus. These results suggest that a 5′-3′ exonuclease activity is essential in these organisms. Our success in constructing a B. subtilis strain that lacked all RNase H genes indicates that the enzymatic activity is dispensable, at least in the wild type. Increasing the 5′-3′ exonuclease activity partially compensated for a defective phenotype of an RNase H-deficient mutant, suggesting cooperative functions for the two enzyme systems. Our search for the distribution of the 5′-3′ exonuclease domain among 250 bacterial genomes resulted in the finding that all eubacteria, but not archaea, possess this domain.
doi:10.1128/JB.00653-07
PMCID: PMC2168925  PMID: 17905985
16.  Crystallization and preliminary crystallographic analysis of bacterial fructosyl amino acid oxidase 
Crystallization of a fructosyl amino acid oxidase from Corynebacterium sp. 2-4-1 yields two forms: one monoclinic and one tetragonal.
Bacterial fructosyl amino acid oxidase [fructosyl α-l-amino acid:oxygen oxidoreductase (defructosylating); EC 1.5.3] has been crystallized by the hanging-drop vapour-diffusion technique using sodium citrate as the precipitant. Two types of crystals were grown: one type are rhombic prismatic yellow crystals that belong to space group C2 with unit-cell parameters a = 101.08, b = 63.36, c = 83.07 Å, β = 108.80° and diffract to at least 1.8 Å resolution, while the second type are rod-like crystals that belong to space group P4122 or P4322 with unit-cell parameters a = b = 119.09, c = 164.66 Å and diffract to 2.7 Å resolution.
doi:10.1107/S1744309104034372
PMCID: PMC1952257  PMID: 16510992
HbA1c; Amadori compound; fructosyl amino acid oxidase
17.  Loop-Mediated Isothermal Amplification Method for Rapid Detection of the Periodontopathic Bacteria Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola 
Journal of Clinical Microbiology  2005;43(5):2418-2424.
Loop-mediated isothermal amplification (LAMP), a novel nucleic acid amplification method, was developed for the rapid detection of the major periodontal pathogens Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola. The LAMP method amplifies DNA with high specificity, efficiency, and rapidity under isothermal conditions using a set of four specially designed primers and a DNA polymerase with strand displacement activity. In this study, we initially designed the primers for LAMP assays to detect these bacteria and evaluated the specificity and sensitivity of these assays. The specificities of the primers for these bacteria were examined using various oral bacteria and various reaction times. The lower detection limits of the 60-min LAMP reaction without loop primers were 1 μg/tube for P. gingivalis, 10 fg/tube for T. forsythia, and 1 ng/tube for T. denticola. Addition of the loop primers for each bacterium improved the detection specificities and sensitivities by several magnitudes. Furthermore, LAMP assays were applied to the rapid detection of these periodontal pathogens in clinical specimens, and the results were compared with those of conventional PCR detection. The results of the LAMP assays corresponded to those of conventional PCR assays. These results indicate that the LAMP assay is an extremely rapid, highly sensitive, specific method. This method is very useful for the rapid detection of periodontopathic bacteria and the diagnosis of periodontal disease.
doi:10.1128/JCM.43.5.2418-2424.2005
PMCID: PMC1153746  PMID: 15872275
18.  Characterization of a Fission Yeast SUMO-1 Homologue, Pmt3p, Required for Multiple Nuclear Events, Including the Control of Telomere Length and Chromosome Segregation 
Molecular and Cellular Biology  1999;19(12):8660-8672.
Unlike ubiquitin, the ubiquitin-like protein modifier SUMO-1 and its budding yeast homologue Smt3p have been shown to be more important for posttranslational protein modification than for protein degradation. Here we describe the identification of the SUMO-1 homologue of fission yeast, which we show to be required for a number of nuclear events including the control of telomere length and chromosome segregation. A disruption of the pmt3+ gene, the Schizosaccharomyces pombe homologue of SMT3, was not lethal, but mutant cells carrying the disrupted gene grew more slowly. The pmt3Δ cells showed various phenotypes such as aberrant mitosis, sensitivity to various reagents, and high-frequency loss of minichromosomes. Interestingly, we found that pmt3+ is required for telomere length maintenance. Loss of Pmt3p function caused a striking increase in telomere length. When Pmt3p synthesis was restored, the telomeres became gradually shorter. This is the first demonstration of involvement of one of the Smt3p/SUMO-1 family proteins in telomere length maintenance. Fusion of Pmt3p to green fluorescent protein (GFP) showed that Pmt3p was predominantly localized as intense spots in the nucleus. One of the spots was shown to correspond to the spindle pole body (SPB). During prometaphase- and metaphase, the bright GFP signals at the SPB disappeared. These observations suggest that Pmt3p is required for kinetochore and/or SPB functions involved in chromosome segregation. The multiple functions of Pmt3p described here suggest that several nuclear proteins are regulated by Pmt3p conjugation.
PMCID: PMC85006  PMID: 10567589

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