Artigo Revisado por pares

Solution structure and dynamics of crh, the bacillus subtilis catabolite repression HPr

2002; Elsevier BV; Volume: 317; Issue: 1 Linguagem: Inglês

10.1006/jmbi.2002.5397

ISSN

1089-8638

Autores

Adrien Favier, Bernhard Brutscher, Martin Blackledge, Anne Galinier, Josef Deutscher, François Pénin, Dominique Marion,

Tópico(s)

RNA and protein synthesis mechanisms

Resumo

The solution structure and dynamics of the Bacillus subtilis HPr-like protein, Crh, have been investigated using NMR spectroscopy. Crh exhibits high sequence identity (45 %) to the histidine-containing protein (HPr), a phospho-carrier protein of the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system, but contains no catalytic His15, the site of PEP-dependent phosphorylation in HPr. Crh also forms a mixture of monomers and dimers in solution whereas HPr is known to be monomeric. Complete backbone and side-chain assignments were obtained for the monomeric form, and 60 % of the dimer backbone resonances; allowing the identification of the Crh dimer interface from chemical-shift mapping. The conformation of Crh was determined to a precision of 0.46(±0.06) Å for the backbone atoms, and 1.01(±0.08) Å for the heavy atoms. The monomer structure is similar to that of known HPr 2.67(±0.22) Å (Cα rmsd), but has a few notable differences, including a change in the orientation of one of the helices (B), and a two-residue shift in β-sheet pairing of the N-terminal strand with the β4 strand. This shift results in a shortening of the surface loop present in HPr and consequently provides a flatter surface in the region of dimerisation contact, which may be related to the different oligomeric nature of these two proteins. A binding site of phospho-serine(P-Ser)-Crh with catabolite control protein A (CcpA) is proposed on the basis of highly conserved surface side-chains between Crh and HPr. This binding site is consistent with the model of a dimer-dimer interaction between P-Ser-Crh and CcpA. 15N relaxation measured in the monomeric form also identified differential local mobility in the helix B which is located in the vicinity of this site.

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