HMM Summary Page: TIGR02025

Functionmagnesium chelatase, H subunit
Gene SymbolbchH
Trusted Cutoff829.00
Domain Trusted Cutoff829.00
Noise Cutoff823.75
Domain Noise Cutoff823.75
Isology Typeequivalog
EC Number6.6.1.1
HMM Length1271
Mainrole CategoryBiosynthesis of cofactors, prosthetic groups, and carriers
Subrole CategoryChlorophyll and bacteriochlorphyll
Gene Ontology TermGO:0005488: binding molecular_function
GO:0010007: magnesium chelatase complex cellular_component
GO:0015995: chlorophyll biosynthetic process biological_process
GO:0016851: magnesium chelatase activity molecular_function
AuthorSelengut J
Entry DateOct 16 2003 11:17AM
Last ModifiedFeb 14 2011 3:27PM
CommentThis HMM represents the H subunit of the magnesium chelatase complex responsible for magnesium insertion into the protoporphyrin IX ring in the biosynthesis of both chlorophyll and bacteriochlorophyll. In chlorophyll-utilizing species, this gene is known as ChlH, while in bacteriochlorophyll-utilizing spoecies it is called BchH. Subunit H is the largest (~140kDa) of the three subunits (the others being BchD/ChlD and BchI/ChlI), and is known to bind protoporphyrin IX. Subunit H is homologous to the CobN subunit of cobaltochelatase and by anology with that enzyme, subunit H is believed to also bind the magnesium ion which is inserted into the ring. In conjunction with the hydrolysis of ATP by subunits I and D, a conformation change is believed to happen in subunit H causing the magnesium ion insertion into the distorted protoporphyrin ring [1].
ReferencesRN [1] RM PMID: 12828371 RT Biosynthesis of chlorophylls from protoporphyrin IX. RA Willows RD. RL Nat Prod Rep. 2003 Jun;20(3):327-41.
Genome PropertyGenProp0144: chlorophyllide a biosynthesis from protoporphyrin IX (HMM)