HMM Summary Page: TIGR02026

Functionmagnesium-protoporphyrin IX monomethyl ester anaerobic oxidative cyclase
Gene SymbolbchE
Trusted Cutoff481.35
Domain Trusted Cutoff481.35
Noise Cutoff328.80
Domain Noise Cutoff328.80
Isology Typeequivalog
HMM Length497
AuthorSelengut J
Entry DateOct 17 2003 11:54AM
Last ModifiedFeb 14 2011 3:27PM
CommentThis HMM represents the cobalamin-dependent oxidative cyclase, a radical SAM enzyme responsible for forming the distinctive E-ring of the chlorin ring system under anaerobic conditions [1]. This step is essential in the biosynthesis of both bacteriochlorophyll and chlorophyll under anaerobic conditions (a separate enzyme, AcsF, acts under aerobic conditions). This model identifies two clades of sequences, one from photosynthetic, non-cyanobacterial bacteria and another including Synechocystis and several non-photosynthetic bacteria. The function of the Synechocystis gene is supported by gene clustering with other photosynthetic genes, so the purpose of the gene in the non-photosynthetic bacteria is uncertain. Note that homologs of this gene are not found in plants which rely solely on the aerobic cyclase.
ReferencesRN [1] RM PMID: 10841582 RT Anaerobic chlorophyll isocyclic ring formation in Rhodobacter capsulatus requires a cobalamin cofactor. RA Gough SP, Petersen BO, Duus JO. RL Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6908-13.
Genome PropertyGenProp0144: chlorophyllide a biosynthesis from protoporphyrin IX (HMM)