2hcv: Difference between revisions

Pseudomonas stutzeri L-rhamnose isomerase (P. stutzeri L-RhI) can efficiently catalyze the isomerization between various aldoses and ketoses, showing a broad substrate specificity compared to L-RhI from Escherichia coli (E. coli L-RhI). To understand the relationship between structure and substrate specificity, the crystal structures of P. stutzeri L-RhI alone and in complexes with L-rhamnose and D-allose which has different configurations of C4 and C5 from L-rhamnose, were determined at a resolution of 2.0 A, 1.97 A, and 1.97 A, respectively. P. stutzeri L-RhI has a large domain with a (beta/alpha)(8) barrel fold and an additional small domain composed of seven alpha-helices, forming a homo tetramer, as found in E. coli L-RhI and D-xylose isomerases (D-XIs) from various microorganisms. The beta1-alpha1 loop (Gly60-Arg76) of P. stutzeri L-RhI is involved in the substrate binding of a neighbouring molecule, as found in D-XIs, while in E. coli L-RhI, the corresponding beta1-alpha1 loop is extended (Asp52-Arg78) and covers the substrate-binding site of the same molecule. The complex structures of P. stutzeri L-RhI with L-rhamnose and D-allose show that both substrates are nicely fitted to the substrate-binding site. The part of the substrate-binding site interacting with the substrate at the 1, 2, and 3 positions is equivalent to E. coli L-RhI, and the other part interacting with the 4, 5, and 6 positions is similar to D-XI. In E. coli L-RhI, the beta1-alpha1 loop creates an unique hydrophobic pocket at the the 4, 5, and 6 positions, leading to the strictly recognition of L-rhamnose as the most suitable substrate, while in P. stutzeri L-RhI, there is no corresponding hydrophobic pocket where Phe66 from a neighbouring molecule merely forms hydrophobic interactions with the substrate, leading to the loose substrate recognition at the 4, 5, and 6 positions.

2HCV is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_stutzeri Pseudomonas stutzeri]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HCV OCA].

==Reference==

The structures of L-rhamnose isomerase from Pseudomonas stutzeri in complexes with L-rhamnose and D-allose provide insights into broad substrate specificity., Yoshida H, Yamada M, Ohyama Y, Takada G, Izumori K, Kamitori S, J Mol Biol. 2007 Feb 2;365(5):1505-16. Epub 2006 Nov 6. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17141803 17141803]

[[Category: L-rhamnose isomerase]]

[[Category: Izumori, K.]]

[[Category: Kamitori, S.]]

[[Category: Takada, G.]]

[[Category: Yamada, M.]]

[[Category: Yoshida, H.]]