title: Three-dimensional models and structure analysis of corynemycolyltransferases in Corynebacterium glutamicum and Corynebacterium efficiens.
abstract: The corynemycolyltransferase proteins were identified from Corynebacterium glutamicum and Corynebacterium efficiens genomes using computational tools available in the public domain. Three-dimensional models were constructed for corynemycolyltransferases based on the crystal structures of related mycolyltransferases in Mycobacterium tuberculosis using the comparative modeling methods. The corynemycolyltransferases share overall an alpha/beta-fold characteristic of the mycolyltransferases despite low sequence identity (<20%) shared by some of the corynemycolyltransferases. However, a significant difference is observed in the region between amino acid residues Trp82-Trp97 and Ala222-Asn223 corresponding to mycolyltransferases. The specificity pockets defined by interactions with the trehalose substrate observed in the crystal structure complex of Ag85B mycolyltransferase (PDB code: 1F0P) suggests that trehalose may not bind some corynemycolyltransferases. This is due to critical mutations in corynemycolyltransferase binding subsites that lead to loss of equivalent side-chain interactions with trehalose and unfavorable steric interactions, particularly, in the case of cmytC gene and the protein corresponding to the gene identifier CE0356 with the equivalent Ala222-Asn223 "long insertion loop". Further, the fibronectin binding region (Phe58-Val69), in mycolyltransferases associated with mediating host-pathogen interactions in M. tuberculosis comprises amino acid residue mutations in the corresponding region in the soil bacterium--Corynebacterium corynemycolyltransferases, that suggest a different epitope and therefore possible lack of binding to fibronectin. The corynemycolyltransferase cmytA responsible for the cell shape formation and for maintaining the cell surface integrity is associated with a C-terminal domain that we have recently shown to comprise tandem amino acid sequence repeats that is likely to be associated with a regular secondary structural motif.
authors.affiliation: School of Chemistry, University of Hyderabad, Hyderabad 500 046, India.
authors.forename: Swathi
authors.initials: S
authors.lastname: Adindla
authors.forename: Kunchur
authors.initials: K
authors.lastname: Guruprasad
authors.forename: Lalitha
authors.initials: L
authors.lastname: Guruprasad
mesh_terms: D000217:Acyltransferases / Q000737:chemistry*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D003352:Corynebacterium / Q000201:enzymology* / Q000235:genetics; D016678:Genome; D008956:Models, Chemical; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D014199:Trehalose / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D014199:Trehalose; D000217:Acyltransferases