2f59

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Revision as of 08:15, 21 November 2007

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spinqualitylabelsall models 2f59, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Lumazine synthase RibH1 from Brucella abortus (Gene BruAb1_0785, Swiss-Prot entry Q57DY1) complexed with inhibitor 5-Nitro-6-(D-Ribitylamino)-2,4(1H,3H) Pyrimidinedione

Overview

6,7-Dimethyl-8-ribityllumazine synthase (lumazine synthase; LS) catalyzes, the penultimate step in the biosynthesis of riboflavin in plants and, microorganisms. This protein is known to exhibit different quaternary, assemblies between species, existing as free pentamers, decamers (dimers, of pentamers) and icosahedrally arranged dodecamers of pentamers. A, phylogenetic analysis on eubacterial, fungal and plant LSs allowed us to, classify them into two categories: Type I LSs (pentameric or icosahedral), and Type II LSs (decameric). The Rhizobiales represent an order of, alpha-proteobacteria that includes, among others, the genera, Mesorhizobium, Agrobacterium and Brucella. Here, we present structural and, kinetic studies on several LSs from Rhizobiales. Interestingly, Mesorhizobium and Brucella encode both a Type-I LS and a Type-II LS called, RibH1 and RibH2, respectively. We show that Type II LSs appear to be, almost inactive, whereas Type I LSs present a highly variable catalytic, activity according to the genus. Additionally, we have solved four, RibH1/RibH2 crystallographic structures from the genera Mesorhizobium and, Brucella. The relationship between the active-site architecture and, catalytic properties in these isoenzymes is discussed, and a model that, describes the enzymatic behavior is proposed. Furthermore, sequence, alignment studies allowed us to extend our results to the genus, Agrobacterium. Our results suggest that the selective pressure controlling, the riboflavin pathway favored the evolution of catalysts with low, reaction rates, since the excess of flavins in the intracellular pool in, Rhizobiales could act as a negative factor when these bacteria are exposed, to oxidative or nitrosative stress.

About this Structure

2F59 is a Single protein structure of sequence from Brucella abortus with CA and INI as ligands. Active as Riboflavin synthase, with EC number 2.5.1.9 Full crystallographic information is available from OCA.

Reference

Structural and Kinetic Properties of Lumazine Synthase Isoenzymes in the Order Rhizobiales., Klinke S, Zylberman V, Bonomi HR, Haase I, Guimaraes BG, Braden BC, Bacher A, Fischer M, Goldbaum FA, J Mol Biol. 2007 Aug 21;. PMID:17854827

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