Derivatives of bacterial bifunctional penicillin binding proteins

摘要

There are described polypeptides which are water-soluble active derivatives of a bacterial bifunctional penicillin binding protein (PBP), said PBP being capable of exhibiting transglycosylase and transpeptidase activity and being bound to the cell membrane, when expressed in a bacterial cell, wherein said derivative is selected from one which: (i) lacks a membrane anchoring sequence but is able to exhibit at least one of said enzyme activities: (ii) lacks transglycosylase activity but retains transpeptidase activity. The polypeptide may comprise a fusion protein, linked via a cleavage site, the second sequence of which permits binding to an affinity matrix (preferably, glutathione-S-transferase or an oligopeptide rich in histidine residues). The bacterial cell may be Escherichia coli or Streptococcus pneumoniae. DNA sequences for the polypeptides, together with cells and vectors comprising such sequences are disclosed. The polypeptides may be used to assay, and design, therapeutic compounds having PBP affinity.