The PASTA domain is found at the C-termini of several Penicillin-binding proteins (PBP) and bacterial serine/threonine kinases. It binds the beta-lactam stem, which implicates it in sensing D-alanyl-D-alanine - the PBP transpeptidase substrate. In PknB of Mycobacterium tuberculosis (P71584), all of the extracellular portion is predicted to be made up of four PASTA domains, which strongly suggests that it is a signal-binding sensor domain. The domain has also been found in proteins involved in cell wall biosynthesis, where it is implicated in localizing the biosynthesis complex to unlinked peptidoglycan.
PASTA is a small globular fold consisting of 3 beta-sheets and an alpha-helix, with a loop region of variable length between the first and second beta-strands. The name PASTA is derived from PBP and Serine/Threonine kinase Associated domain [(PUBMED:12217513)].
The PASTA domain (for penicillin-binding protein and serine/threonine kinase associated domain) is found in the high molecular weight penicillin-binding proteins and eukaryotic-like serine/threonine kinases of a range of pathogens. We describe this previously uncharacterized domain and infer that it binds beta-lactam antibiotics and their peptidoglycan analogues. We postulate that PknB-like kinases are key regulators of cell-wall biosynthesis. The essential function of these enzymes suggests an additional pathway for the action of beta-lactam antibiotics.
Crystal structure of a deacylation-defective mutant of penicillin-bindingprotein 5 at 2.3-A resolution.
J Biol Chem. 2001; 276: 616-23
Display abstract
Penicillin-binding protein 5 (PBP 5) of Escherichia coli functions as ad-alanine carboxypeptidase, cleaving the C-terminal d-alanine residue fromcell wall peptides. Like all PBPs, PBP 5 forms a covalent acyl-enzymecomplex with beta-lactam antibiotics; however, PBP 5 is distinguished byits high rate of deacylation of the acyl-enzyme complex (t(12)approximately 9 min). A Gly-105 --> Asp mutation in PBP 5 markedly impairsthis beta-lactamase activity (deacylation), with only minor effects onacylation, and promotes accumulation of a covalent complex with peptidesubstrates. To gain further insight into the catalytic mechanism of PBP 5,we determined the three-dimensional structure of the G105D mutant form ofsoluble PBP 5 (termed sPBP 5') at 2.3 A resolution. The structure iscomposed of two domains, a penicillin binding domain with a strikingsimilarity to Class A beta-lactamases (TEM-1-like) and a domain of unknownfunction. In addition, the penicillin-binding domain contains an activesite loop spatially equivalent to the Omega loop of beta-lactamases. Inbeta-lactamases, the Omega loop contains two amino acids involved incatalyzing deacylation. This similarity may explain the highbeta-lactamase activity of wild-type PBP 5. Because of the low rate ofdeacylation of the G105D mutant, visualization of peptide substrates boundto the active site may be possible.
Metabolism (metabolic pathways involving proteins which contain this domain)
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This information is based on mapping of SMART genomic protein database to KEGG orthologous groups. Percentage points are related to the number of proteins with PASTA domain which could be assigned to a KEGG orthologous group, and not all proteins containing PASTA domain. Please note that proteins can be included in multiple pathways, ie. the numbers above will not always add up to 100%.
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