1a04
From Proteopedia
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THE STRUCTURE OF THE NITRATE/NITRITE RESPONSE REGULATOR PROTEIN NARL IN THE MONOCLINIC C2 CRYSTAL FORM
Overview
The structure of the Escherichia coli response regulator NarL has been, solved in a new, monoclinic space group, and compared with the earlier, orthorhombic crystal structure. Because the monoclinic crystal has two, independent NarL molecules per asymmetric unit, we now have three, completely independent snapshots of the NarL molecule: two from the, monoclinic form and one from the orthorhombic. Comparison of these three, structures shows the following: (a) The pairing of N and C domains of the, NarL molecule proposed from the earlier analysis is in fact correct, although the polypeptide chain connecting domains was, and remains, disordered and not completely visible. The new structure exhibits, identical relative orientation of N and C domains, and supplies some of, the missing residues, leaving a gap of only seven amino acids. (b), Examination of corresponding features in the three independent NarL, molecules shows that deformations in structure produced by crystal packing, are negligible. (c) The "telephone receiver" model of NarL activation is, confirmed. The N domain of NarL blocks the binding of DNA to the C domain, that would be expected from the helix-turn-helix structure of the C, domain. Hence, binding can only occur after significant displacement of N, and C domains. (d) NarL monomers have a strong tendency toward, dimerization involving contacts between helixes alpha 1 in the two, monomers, and this may have mechanistic significance in DNA binding., Analogous involvement of helix alpha 1 in intermolecular contacts is also, found in UhpA and in the CheY/CheZ complex.
About this Structure
1A04 is a Single protein structure of sequence from Escherichia coli. Structure known Active Site: 1. Full crystallographic information is available from OCA.
Reference
NarL dimerization? Suggestive evidence from a new crystal form., Baikalov I, Schroder I, Kaczor-Grzeskowiak M, Cascio D, Gunsalus RP, Dickerson RE, Biochemistry. 1998 Mar 17;37(11):3665-76. PMID:9521685
Page seeded by OCA on Mon Nov 5 13:11:53 2007
