|Gene:||pbpG||Accession Numbers: EG12015 (MetaCyc), b2134, ECK2127|
Synonyms: yohB, PBP7, PBP8
Species: Escherichia coli K-12 substr. MG1655
PBP7 is a DD-endopeptidase and is a member of the family of penicillin-binding proteins. It is involved as a auxiliary factor in maintaining the rod shape of the murein sacculus. PBP7 acts by hydrolysing D-alanyl-DAP amide bonds within murein crosslinks.
PPB7 is a soluble, periplasmic protein that is loosely membrane associated [Henderson95, Barbas86]. PBP7 has consensus motifs putting it in the family of penicillin-binding endopeptidases, as well as a signal-sequence cleavage site where its amino-terminus is clipped and a site near the carboxy-terminus where OmpT cleaves it to yield the derivative protein PBP8 [Henderson95]. This latter cleavage is a preparation artifact, as it only occurs following cell lysis or freeze-thaw perturbation of membranes [Henderson94a].
Both PBP7 and its cleavage derivative, PBP8 have D-alanyl-DAP endopeptidase activity capable of cleaving the bonds in murein sacculi but not in dimeric muropeptides [Romeis94a]. PBP7 also has minor LD-endopeptidase activity allowing it to hydrolyze some DAP-DAP murein crosslinks [Romeis94a]. A pbpG deletion mutant has no obvious growth defects [Hara96, Henderson95]. Overexpression of pbpG also had no effect on growth [Henderson95]. dacA pbpG double mutants have an increased percentage of pentapeptides, increased numbers of crosslinkages, decreased attachment of peptidoglycan to Lpp, and an increased rate of abnormal cell morphology which was exacerbated by further deletion of dacB [Meberg04], dacC, or ampC [Nelson01, Varma07]. A ftsZ84 dacA pbpG mutant has an increased branching phenotype [Varma04]. ftsZ84 dacA pbpG or ftsZ84 dacB pbpG mutants lyse at the nonpermissive temperature [Varma04]. Inhibition of FtsZ by SulA in a dacA pbpG mutant results in growth of spiral-shaped cells [Varma04]. Further inhibition of MreB or PBP2 in FtsZ-inhibited dacA pbpG mutants results in lemon shaped cells with polar, tubular extensions [Varma07]. Deletion of pbpG in combination with other endopeptidases and amiC results in increased chaining due to deficient septum cleavage during cell division [Priyadarshini06]. pbpG acts as a multicopy suppressor of spr thermosensitivity, which is dependent on the active site serine of PBP7 [Hara96]. PBP8 levels are increased in minicells [Obermann94].
PBP7 binds a number of antibiotics capable of lysing non-growing cells [Tuomanen87]. PBP7 binds soluble lytic murein transglycosylase, stimulating its enzymatic activity via direct interaction and stabilizing it in vitro> [Romeis94].
Locations: periplasmic space
|Map Position: [2,221,960 <- 2,222,892]|
Molecular Weight of Polypeptide: 33.887 kD (from nucleotide sequence), 32.0 kD (experimental) [Spratt77a ]
Unification Links: ASAP:ABE-0007050 , CGSC:36349 , DIP:DIP-48108N , EchoBASE:EB1952 , EcoGene:EG12015 , EcoliWiki:b2134 , ModBase:P0AFI5 , OU-Microarray:b2134 , PortEco:pbpG , PR:PRO_000023497 , Protein Model Portal:P0AFI5 , RefSeq:NP_416638 , RegulonDB:EG12015 , SMR:P0AFI5 , String:511145.b2134 , UniProt:P0AFI5
|Biological Process:||GO:0000270 - peptidoglycan metabolic process
GO:0042493 - response to drug [Tuomanen87]
GO:0043093 - FtsZ-dependent cytokinesis [Priyadarshini06]
GO:0071555 - cell wall organization [UniProtGOA11, Romeis94a]
GO:0006508 - proteolysis [GOA01]
GO:0008360 - regulation of cell shape [UniProtGOA11]
GO:0009252 - peptidoglycan biosynthetic process [UniProtGOA11]
|Molecular Function:||GO:0004175 - endopeptidase activity
GO:0009002 - serine-type D-Ala-D-Ala carboxypeptidase activity [GOA01]
GO:0016787 - hydrolase activity [UniProtGOA11]
|Cellular Component:||GO:0030288 - outer membrane-bounded periplasmic space
GO:0042597 - periplasmic space [UniProtGOA11a, UniProtGOA11]
|MultiFun Terms:||cell processes → cell division|
|cell processes → protection → drug resistance/sensitivity|
|cell structure → murein|
|metabolism → biosynthesis of macromolecules (cellular constituents) → murein (peptidoglycan)|
Enzymatic reaction of: DD-endopeptidase (penicillin-binding protein 7)
EC Number: 3.4.-.-
peptidoglycan D-alanyl-DAP crosslink[periplasmic space] + H2O[periplasmic space] <=> peptidoglycan tetrapeptide, glycan chain 1[periplasmic space] + peptidoglycan tetrapeptide, glycan chain 2[periplasmic space]
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
The reaction is physiologically favored in the direction shown.
T(opt): 43 °C [Romeis94a]
pH(opt): 6.2 [Romeis94a]
|Feature Class||Location||Common Name||Citations||Comment|
|Signal-Sequence||1 -> 25|
|Signal-Sequence||1 -> 28||PBP7 signal sequence|
|Chain||26 -> 310|
Peter D. Karp on Wed Jan 18, 2006:
Gene right-end position adjusted based on analysis performed in the 2005 E. coli annotation update [Riley06 ].
10/20/97 Gene b2134 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG12015; confirmed by SwissProt match.
Barbas86: Barbas JA, Diaz J, Rodriguez-Tebar A, Vazquez D (1986). "Specific location of penicillin-binding proteins within the cell envelope of Escherichia coli." J Bacteriol 165(1);269-75. PMID: 3510188
Denome99: Denome SA, Elf PK, Henderson TA, Nelson DE, Young KD (1999). "Escherichia coli mutants lacking all possible combinations of eight penicillin binding proteins: viability, characteristics, and implications for peptidoglycan synthesis." J Bacteriol 181(13);3981-93. PMID: 10383966
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Fischer89: Fischer E (1989). "Osmolability of Escherichia coli and modification of [125I]ampicillin-binding by competence induction for uptake of transforming DNA." Arch Microbiol 153(1);43-6. PMID: 2692534
Hara96: Hara H, Abe N, Nakakouji M, Nishimura Y, Horiuchi K (1996). "Overproduction of penicillin-binding protein 7 suppresses thermosensitive growth defect at low osmolarity due to an spr mutation of Escherichia coli." Microb Drug Resist 2(1);63-72. PMID: 9158724
Henderson94a: Henderson TA, Dombrosky PM, Young KD (1994). "Artifactual processing of penicillin-binding proteins 7 and 1b by the OmpT protease of Escherichia coli." J Bacteriol 176(1);256-9. PMID: 8282705
Henderson97: Henderson TA, Young KD, Denome SA, Elf PK (1997). "AmpC and AmpH, proteins related to the class C beta-lactamases, bind penicillin and contribute to the normal morphology of Escherichia coli." J Bacteriol 179(19);6112-21. PMID: 9324260
Leidenix89: Leidenix MJ, Jacoby GH, Henderson TA, Young KD (1989). "Separation of Escherichia coli penicillin-binding proteins into different membrane vesicles by agarose electrophoresis and sizing chromatography." J Bacteriol 171(10);5680-6. PMID: 2676988
Meberg04: Meberg BM, Paulson AL, Priyadarshini R, Young KD (2004). "Endopeptidase penicillin-binding proteins 4 and 7 play auxiliary roles in determining uniform morphology of Escherichia coli." J Bacteriol 186(24);8326-36. PMID: 15576782
Nelson01: Nelson DE, Young KD (2001). "Contributions of PBP 5 and DD-carboxypeptidase penicillin binding proteins to maintenance of cell shape in Escherichia coli." J Bacteriol 183(10);3055-64. PMID: 11325933
Priyadarshini06: Priyadarshini R, Popham DL, Young KD (2006). "Daughter cell separation by penicillin-binding proteins and peptidoglycan amidases in Escherichia coli." J Bacteriol 188(15);5345-55. PMID: 16855223
Riley06: Riley M, Abe T, Arnaud MB, Berlyn MK, Blattner FR, Chaudhuri RR, Glasner JD, Horiuchi T, Keseler IM, Kosuge T, Mori H, Perna NT, Plunkett G, Rudd KE, Serres MH, Thomas GH, Thomson NR, Wishart D, Wanner BL (2006). "Escherichia coli K-12: a cooperatively developed annotation snapshot--2005." Nucleic Acids Res 34(1);1-9. PMID: 16397293
Romeis94: Romeis T, Holtje JV (1994). "Specific interaction of penicillin-binding proteins 3 and 7/8 with soluble lytic transglycosylase in Escherichia coli." J Biol Chem 269(34);21603-7. PMID: 8063800
Satta95: Satta G, Cornaglia G, Mazzariol A, Golini G, Valisena S, Fontana R (1995). "Target for bacteriostatic and bactericidal activities of beta-lactam antibiotics against Escherichia coli resides in different penicillin-binding proteins." Antimicrob Agents Chemother 39(4);812-8. PMID: 7785976
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