Electronic Resource
Copenhagen
:
International Union of Crystallography (IUCr)
Acta crystallographica
56 (2000), S. 115-128
ISSN:
1399-0047
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The porphobilinogen synthase (PBGS) family of enzymes catalyzes the first common step in the biosynthesis of the essential tetrapyrroles such as chlorophyll and porphyrin. Although PBGSs are highly conserved at all four levels of protein structure, there is considerable diversity in the use of divalent cations for the catalytically essential and allosteric roles. Assumptions regarding commonalities among the PBGS proteins coupled with the diversity of usage of metal ions has led to a confused literature. The recent publication of crystal structures for three PBGS proteins coupled with more than 50 individual PBGS sequences allows an evaluation of these assumptions. This topical review focuses on the usage of metals by the PBGS family of proteins. It raises doubt concerning a dogma that there has been an evolutionary shift between ZnII and MgII at one or more of the divalent metal-binding sites. It also raises the possibility that there may be up to four specific divalent metal ion-binding sites, each serving a unique function that can be alternatively filled by amino acids in some of the PBGSs.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0907444999014894
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