Histidine-binding protein

The periplasmic binding proteins function together with the other subunits of the ABC transporter system. One of the best understood systems is encoded by the histidine transport operon of Salmonella typhimurium,445 453 There are four genes his (encoding the histidine-binding protein), hisQ, hisM, and hisP. 

Figure 8-24 (A) MolScript ribbon drawing of the periplasmic histidine-binding protein HisJ, a component of an ABC transporter system of Salmonella. The bound L-histidine is shown as a ball-and-stick model. (B) Stereoscopic view of the histidinebinding site showing hydrogen-bonding interactions of protein side chains with the histidine. From Oh et al.i60 Courtesy of Giovanna Ferro-Luzzi Ames.

There are four genes his (encoding the histidine-binding protein), hisQ, hisM, and hisP. 

The world of zinc-containing DNA-binding proteins is by no means exhausted by these three subfamilies. Several other subfamilies are already known with different three-dimensional structures and different sequence patterns of cysteine and histidine residues that form the zinc ligands. Further subfamilies may well be discovered as the genomes of different species are sequenced whether or not any fundamentally new principles for DNA-protein recognition will be discovered amongst these new subfamilies remains to be seen. 

Histidine phosphatases and aspartate phosphatases are well established in lower organisms, mainly in bacteria and in context with two-component-systems . Reversible phosphorylation of histidine residues in vertebrates is in its infancy. The first protein histidine phosphatase (PHP) from mammalian origin was identified just recently. The soluble 14 kD protein does not resemble any of the other phosphatases. ATP-citrate lyase and the (3-subunit of heterotrimeric GTP-binding proteins are substrates of PHP thus touching both, metabolic pathways and signal transduction [4]. 

Prossnitz, E., Nikaido, K., Ulbrich, S.J., and Ames, G.F. (1988) Formaldehyde and photoactivatable cross-linking of the periplasmic binding protein to a membrane component of the histidine transport system of Salmonella typhimurium. J. Biol. Chem. 263, 17917-17920. 

Activation parameters for the reaction of NO with metMb, Eq. (15), were determined in this laboratory and in collaboration with van Eldik and Stochel (Table II) (23). Comparison of these activation parameters with those determined for reactions of NO with the water soluble ferri-heme complexes Fem(TPPS)(H20)2 and Feni(TMPS)(H20)2 (Table II) demonstrate that the latter compounds represent reasonable models for the kinetics for the analogous reaction with metMb. For example, the kon step would appear to be defined largely by the H20 lability of metMb(H20), although it is clear that the diffusion through protein channels, the distal residues and the proximal histidine binding to the Fe(III) center must all influence the NO binding kinetics (23,24). These properties may indeed be reflected in the lower AS values for both the on and off reactions on metMb. In a related study, Cao et al. recently... 

The best-studied systems to date are those for the uptake of maltose, histidine, siderophores and vitamin B12. Typical of all the ABC-type importers are the soluble binding proteins, which bind the substrate with high affinity. Early studies revealed that many binding proteins could be extracted from Gramnegative bacteria by an osmotic shock procedure, giving rise to the term osmotic-shock-sensitive transport systems. It still holds true that the majority... 

Cysteine can bind to either one or two metal ions, and is frequently found as a ligand to iron (in Fe-S clusters—see later) and to Cu+ (for example in the copper chaperones, which transfer copper to specific copper-binding proteins). Histidine can bind metal ions in two... 

HAMP HAMP (Histidine kinases, Adenylyl cyclases, Methyl binding proteins, Phosphatases) domain E(MF)AB 0(0) 0(0) ... 

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