1A04

THE STRUCTURE OF THE NITRATE/NITRITE RESPONSE REGULATOR PROTEIN NARL IN THE MONOCLINIC C2 CRYSTAL FORM

Summary for 1A04

• Entry DOI: 10.2210/pdb1a04/pdb
• Descriptor: NITRATE/NITRITE RESPONSE REGULATOR PROTEIN NARL (2 entities in total)
• Functional Keywords: signal transduction protein, response regulators, two-component systems
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 47657.25

Authors

Baikalov, I.,Schroder, I.,Kaczor-Grzeskowiak, M.,Cascio, D.,Gunsalus, R.P.,Dickerson, R.E. (deposition date: 1997-12-08, release date: 1998-03-18, Last modification date: 2024-05-22)

Primary citation

Baikalov, I.,Schroder, I.,Kaczor-Grzeskowiak, M.,Cascio, D.,Gunsalus, R.P.,Dickerson, R.E.
NarL dimerization? Suggestive evidence from a new crystal form
Biochemistry, 37:3665-3676, 1998

PubMed Abstract: 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.

PubMed: 9521685
DOI: 10.1021/bi972365a

Experimental method

X-RAY DIFFRACTION (2.2 Å)