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1.  Enhanced expression of codon optimized Mycobacterium avium subsp. paratuberculosis antigens in Lactobacillus salivarius 
It is well documented that open reading frames containing high GC content show poor expression in A+T rich hosts. Specifically, G+C-rich codon usage is a limiting factor in heterologous expression of Mycobacterium avium subsp. paratuberculosis (MAP) proteins using Lactobacillus salivarius. However, re-engineering opening reading frames through synonymous substitutions can offset codon bias and greatly enhance MAP protein production in this host. In this report, we demonstrate that codon-usage manipulation of MAP2121c can enhance the heterologous expression of the major membrane protein (MMP), analogous to the form in which it is produced natively by MAP bacilli. When heterologously over-expressed, antigenic determinants were preserved in synthetic MMP proteins as shown by monoclonal antibody mediated ELISA. Moreover, MMP is a membrane protein in MAP, which is also targeted to the cellular surface of recombinant L. salivarius at levels comparable to MAP. Additionally, we previously engineered MAP3733c (encoding MptD) and show herein that MptD displays the tendency to associate with the cytoplasmic membrane boundary under confocal microscopy and the intracellularly accumulated protein selectively adheres to the MptD-specific bacteriophage fMptD. This work demonstrates there is potential for L. salivarius as a viable antigen delivery vehicle for MAP, which may provide an effective mucosal vaccine against Johne's disease.
PMCID: PMC4154528  PMID: 25237653
MAP antigens; MptD; MMP; codon optimization; expression host; paratuberculosis; MAP vaccine; Johne's disease
2.  In silico modeling of the staphylococcal bacteriophage-derived peptidase CHAPK 
Bacteriophage  2011;1(4):198-206.
The aim of this study was to use comparative modeling to predict the three-dimensional structure of the CHAPK protein (cysteine, histidine-dependent amidohydrolase/peptidase domain of the LysK endolysin, derived from bacteriophage K). Iterative PSI-BLAST searches against the Protein Data Bank (PDB) and nonredundant (nr) databases were used to populate a multiple alignment for analysis using the T-Coffee Expresso server. A consensus Maximum Parsimony phylogenetic tree with a bootstrap analysis setting of 1,000 replicates was constructed using MEGA4. Structural templates relevant to our target (CHAPK) were identified, processed in Expresso and used to generate a 3D model in the alignment mode of SWISS-MODEL. These templates were also processed in the I-TASSER web server. A Staphylococcus saprophyticus CHAP domain protein, 2K3A, was identified as the structural template in both servers. The I-TASSER server generated the CHAPK model with the best bond geometries when analyzed using PROCHECK and the most logical organization of the structure. The predicted 3D model indicates that CHAPK has a papain-like fold. Circular dichroism spectropolarimetry also indicated that CHAPK has an αβ fold, which is consistent with the model presented. The putative active site maintained a highly conserved Cys54-His117-Glu134 charge relay and an oxyanion hole residue Asn136. The residue triplet, Cys-His-Glu, is known to be a viable proteolytic triad in which we predict the Cys residue is used in a nucleophilic attack on peptide bonds at a specific site in the pentaglycine cross bridge of staphylococcal cell wall peptidoglycan. Use of comparative modeling has allowed approximation of the 3D structure of CHAPK giving information on the structure and an insight into the binding and active site of the catalytic domain. This may facilitate its development as an alternative antibacterial agent.
PMCID: PMC3448105  PMID: 23050213
bacteriophage; CHAP; endolysin; in silico; peptidase; staphylococcus

Results 1-2 (2)