1rba
From Proteopedia
|
SUBSTITUTION OF ASP193 TO ASN AT THE ACTIVE SITE OF RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE RESULTS IN CONFORMATIONAL CHANGES
Overview
The crystal structure of a mutant of ribulose bisphosphate, carboxylase/oxygenase from Rhodospirillium rubrum, where Asp193, one of, the ligands of the magnesium ion at the activator site, is replaced by, Asn, has been determined to a nominal resolution of 0.26 nm. The mutation, of Asp to Asn induces both local and global conformation changes as, follows. The side chain of Asn193 moves away from the active site and, interacts with main-chain oxygen of residue 165, located in the, neighbouring strand beta 1 of the alpha/beta barrel. The side chain of, Lys166, which forms a salt bridge with Asp193 in the wild-type enzyme, interacts with Asn54 from the second subunit and creates a new, subunit-subunit interaction. Another new subunit-subunit interaction is, formed, more than 1.2 nm away from the site of the mutation. In the mutant, enzyme, the side chain of Asp263 interacts with the side chain of Thr106, from the second subunit. Asp193 is not part of a subunit-subunit interface, area or an allosteric regulatory site. Nevertheless, replacement of this, residue by Asn results, unexpectedly, in a difference in the packing of, the two subunits, which can be described as a slight rotation of one of, the subunits relative to the second. The observed structural changes at, the active site of the enzyme provide a molecular explanation for the, differing behaviour of the Asp193----Asn mutant with respect to, activation.
About this Structure
1RBA is a Single protein structure of sequence from Rhodospirillum rubrum. Active as Ribulose-bisphosphate carboxylase, with EC number 4.1.1.39 Full crystallographic information is available from OCA.
Reference
Substitution of ASP193 to ASN at the active site of ribulose-1,5-bisphosphate carboxylase results in conformational changes., Soderlind E, Schneider G, Gutteridge S, Eur J Biochem. 1992 Jun 15;206(3):729-35. PMID:1606957
Page seeded by OCA on Wed Nov 21 01:25:55 2007
