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1.  Isolation, sequencing, and heterologous expression of the Paecilomyces variotii gene encoding S-hydroxymethylglutathione dehydrogenase (fldA) 
The filamentous fungus Paecilomyces variotii NBRC 109023 (teleomorph: Byssochlamys spectabilis NBRC 109023) degrades formaldehyde at concentrations as high as 2.4 % (w/v). In many prokaryotes and in all known eukaryotes, formaldehyde degradation is catalyzed by S-hydroxymethylglutathione (S-HMGSH) dehydrogenase. We report here the isolation and characterization of the gene encoding S-HMGSH dehydrogenase activity in P. variotii. The 1.6-kb fldA gene contained 5 introns and 6 exons, and the corresponding cDNA was 1143 bp, encoding a 40-kDa protein composed of 380 amino acids. FldA was predicted to have 74.3, 73.7, 68.5, and 67.4 % amino acid identity to the S-HMGSH dehydrogenases of Hansenula polymorpha, Candida boidinii, Saccharomyces cerevisiae, and Kluyveromyces lactis, respectively. The predicted protein also showed high amino acid similarity (84∼86 %) to the products of putative fldA genes from other filamentous fungi, including Aspergillus sp. and Penicillium sp. Notably, the P. variotii fldA gene was able to functionally complement a Saccharomyces cerevisiae strain (BY4741 ∆sfa1) lacking the gene for S-HMGSH dehydrogenase. The heterologous expression construct rendered BY4741 ∆sfa1 tolerant to exogenous formaldehyde. Although BY4741 (parental wild-type strain) was unable to degrade even low concentrations of formaldehyde, BY4741 ∆sfa1 harboring Paecilomyces fldA was able to degrade 4 mM formaldehyde within 30 h. The findings from this study confirm the essential role of S-HMGSH dehydrogenase in detoxifying formaldehyde.
Electronic supplementary material
The online version of this article (doi:10.1007/s00253-014-6203-8) contains supplementary material, which is available to authorized users.
doi:10.1007/s00253-014-6203-8
PMCID: PMC4322224  PMID: 25398285
Paecilomyces variotii; Formaldehyde degradation; S-hydroxymethylglutathione dehydrogenase; fldA; Heterologous expression
2.  Draft Genome Sequence of the Formaldehyde-Resistant Fungus Byssochlamys spectabilis No. 5 (Anamorph Paecilomyces variotii No. 5) (NBRC109023) 
Genome Announcements  2014;2(1):e01162-13.
Byssochlamys spectabilis no. 5 (anamorph Paecilomyces variotii no. 5) (NBRC109023) was isolated from a soil sample in 2001 in Kumamoto Prefecture, Japan. This fungus is highly resistant to formaldehyde. Here, we report a draft genome sequence of P. variotii no. 5; this draft was produced with the intent of investigating the mechanism of formaldehyde resistance. This is the first report of the genome sequence of any Paecilomyces species.
doi:10.1128/genomeA.01162-13
PMCID: PMC3886963  PMID: 24407650
3.  Purification and properties of S-hydroxymethylglutathione dehydrogenase of Paecilomyces variotii no. 5, a formaldehyde-degrading fungus 
AMB Express  2012;2:32.
S-hydroxymethylglutathione dehydrogenase from Paecilomyces variotii No. 5 strain (NBRC 109023), isolated as a formaldehyde-degrading fungus, was purified by a procedure that included ammonium sulfate precipitation, DEAE-Sepharose and hydroxyapatite chromatography and isoelectrofocusing. Approximately 122-fold purification was achieved with a yield of 10.5%. The enzyme preparation was homogeneous as judged by sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE). The molecular mass of the purified enzyme was estimated to be 49 kDa by SDS-PAGE and gel filtration, suggesting that it is a monomer. Enzyme activity was optimal at pH 8.0 and was stable in the range of pH 7.0–10. The optimum temperature for activity was 40°C and the enzyme was stable up to 40°C. The isoelectric point was pH 5.8. Substrate specificity was very high for formaldehyde. Besides formaldehyde, the only aldehyde or alcohol tested that served as a substrate was pyruvaldehyde. Enzyme activity was enhanced by several divalent cations such as Mn2+ (179%), Ba2+ (132%), and Ca2+ (112%) but was completely inhibited by Ni2+, Fe3+, Hg2+, p-chloromercuribenzoate (PCMB) and cuprizone. Inactivation of the enzyme by sulfhydryl reagents (Hg2+ and PCMB) indicated that the sulfhydryl group of the enzyme is essential for catalytic activity.
doi:10.1186/2191-0855-2-32
PMCID: PMC3439253  PMID: 22731626
S-hydroxymethylglutathione dehydrogenase; Enzyme purification; Formaldehyde metabolism; Paecilomyces variotii; SH enzyme
4.  Progressive Rearrangement of Telomeric Sequences Added to Both the ITR Ends of the Yeast Linear pGKL Plasmid 
Relocation into the nucleus of the yeast cytoplasmic linear plasmids was studied using a monitor plasmid pCLU1. In Saccharomyces cerevisiae, the nuclearly-relocated pCLU1 replicated in a linear form (termed pTLU-type plasmid) which carried the host telomeric repeats TG1-3 of 300-350 bp at both ends. The telomere sequences mainly consisted of a major motif TGTGTGGGTGTGG which was complementary to part of the RNA template of yeast telomerase and were directly added to the very end of the pCLU1-terminal element ITR (inverted terminal repeat), suggesting that the ITR end played a role as a substrate of telomerase. The telomere sequences varied among isolated pTLU-type plasmids, but the TG1-3 organization was symmetrically identical on both ends of any one plasmid. During cell growth under non-selective condition, the telomeric repeat sequences were progressively rearranged on one side, but not on the opposite side of pTLU plasmid ends. This indicates that the mode of telomeric DNA replication or repair differed between both ends. Clonal analysis showed that the intense rearrangement of telomeric DNA was closely associated with extreme instability of pTLU plasmids.
doi:10.1251/bpo44
PMCID: PMC150389  PMID: 12734558
telomere; telomerase; plasmids

Results 1-4 (4)