Disease relevance of rbsK

• Mutants defective in this transport system, but normal for ribokinase , are able to grow normally on high concentrations of the sugar, indicating that there is at least a second, low-affinity transport system for ribose in E. coli K-12 [1].
• The regulatory significance of these sequence features is discussed with respect to the rbs operon. rbsK has been cloned downstream from the Serratia marcescens trp promoter on a multicopy plasmid [2].
• A 7-kb DNA fragment of Lactobacillus sakei, containing the rbsD, rbsK and rbsR genes was sequenced [3].

High impact information on rbsK

• The sites of tagging correspond to ribosome stalling at the termination codon and at rare AGG codons encoding Arg-307 and Arg-309, the antepenultimate and C-terminal residues of E. coli ribokinase [4].
• It includes the 3' terminus of rbsB (the gene for ribose-binding protein) and the entire rbsK gene, encoding ribokinase [2].
• Ribokinase has been purified to homogeneity (216 mumol/min/mg) from a strain harboring this plasmid [2].
• Amino acid compositions of native ribokinase and the C-terminal dodecapeptide agree with the predicted amino acid compositions, confirming the accuracy of the DNA sequence and the translation termination site [2].
• Each subunit is composed of two domains, a larger alpha/beta domain and a smaller beta-sheet domain, similar to that of ribokinase and adenosine kinase, members of the PfkB family of carbohydrate kinases [5].

Biological context of rbsK

• One of the signatures observed in amino acid sequences from the ribokinase familiy members is the NXXE motif, which locates at the active site in the ribokinase fold [6].
• Ribokinase from E. coli: expression, purification, and substrate specificity [7].

Associations of rbsK with chemical compounds

• Cotransduction studies located all of the mutations near ilv, at the same position as previously identified mutations causing defects in ribokinase ( rbsK ) or ribose transport ( rbsP ) [1].
• Cells harboring this plasmid, when grown on minimal ribose plus ampicillin, express ribokinase at the level of 2% of the soluble protein, and induction with indoleacrylic acid raises ribokinase levels another 8-fold [2].
• An X-ray structure of ribokinase in the presence of cesium was solved and refined at 2.34 A resolution [8].
• Ribokinase phosphorylates ribose to form ribose-5-phosphate in the presence of ATP and magnesium [9].
• CONCLUSIONS: Inspection of the complex indicates that ribokinase utilises both a catalytic base for activation of the ribose in nucleophilic attack and an anion hole that stabilises the transition state during phosphoryl transfer [10].

Other interactions of rbsK

• Potential consensus promoter sequences and a stable stem-loop structure are present in the rbsB-rbsK intercistronic region [2].

Analytical, diagnostic and therapeutic context of rbsK

• Purification, characterization, and crystallization of Escherichia coli ribokinase [9].
• We describe an improved purification protocol for Escherichia coli ribokinase and give evidence from light-scattering and gel filtration studies that the protein forms a dimer in solution [9].

References