7s56
Sortase A from Streptococcus agalactiae, residues 79-247
Structural highlights
FunctionSRTA_STRA3 Transpeptidase that anchors surface proteins to the cell wall. Recognizes and modifies its substrate by proteolytic cleavage of a C-terminal sorting signal. Following cleavage, a covalent intermediate is formed via a thioester bond between the sortase and its substrate, which is then transferred and covalently attached to the cell wall. This sortase recognizes a Leu-Pro-x-Thr-Gly (LPXTG) motif, which is cleaved by the sortase between the threonine and glycine residues (By similarity). Essential for adherence to eukaryotic cells and for binding to fibronectin and fibrinogen (PubMed:15908360).[UniProtKB:Q2FV99][1] Publication Abstract from PubMedSequence variation in related proteins is an important characteristic that modulates activity and selectivity. An example of a protein family with a large degree of sequence variation is that of bacterial sortases, which are cysteine transpeptidases on the surface of gram-positive bacteria. Class A sortases are responsible for attachment of diverse proteins to the cell wall to facilitate environmental adaption and interaction. These enzymes are also used in protein engineering applications for sortase-mediated ligations (SML) or sortagging of protein targets. We previously investigated SrtA from Streptococcus pneumoniae, identifying a number of putative beta7-beta8 loop-mediated interactions that affected in vitro enzyme function. We identified residues that contributed to the ability of S. pneumoniae SrtA to recognize several amino acids at the P1' position of the substrate motif, underlined in LPXTG, in contrast to the strict P1' Gly recognition of SrtA from Staphylococcus aureus. However, motivated by the lack of a structural model for the active, monomeric form of S. pneumoniae SrtA, here, we expanded our studies to other Streptococcus SrtA proteins. We solved the first monomeric structure of S. agalactiae SrtA which includes the C-terminus, and three others of beta7-beta8 loop chimeras from S. pyogenes and S. agalactiae SrtA. These structures and accompanying biochemical data support our previously identified beta7-beta8 loop-mediated interactions and provide additional insight into their role in Class A sortase substrate selectivity. A greater understanding of individual SrtA sequence and structural determinants of target selectivity may also facilitate the design or discovery of improved sortagging tools. Structural and biochemical analyses of selectivity determinants in chimeric Streptococcus Class A sortase enzymes.,Gao M, Johnson DA, Piper IM, Kodama HM, Svendsen JE, Tahti E, Longshore-Neate F, Vogel B, Antos JM, Amacher JF Protein Sci. 2021 Dec 22. doi: 10.1002/pro.4266. PMID:34939250[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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