Novel peptide inhibiting both TEM-1 β-lactamase and penicillin-binding proteins.

9G4H9, a catalytic antibody displaying β-lactamase-like activity, has been developed by the anti-idiotypic approach using β-lactamase as the first antigen. Thus 9G4H9 represents the 'internal image' of β-lactamase. We selected a cyclic peptide anchored to a bacteriophage M13 library using 9G4H9 as the target.

Mutational and inhibitory analysis of a catalytic antibody. Implication for drug discovery.

Data on catalytic antibodies (abzymes) having critical roles in pathologies, for example in some auto-immune diseases accumulate at overwhelming pace. Nevertheless, the misunderstanding of how antibodies can mimic a catalytic activity may hamper the development of therapeutic tools. We thus investigated the structure function roles of residues of a catalytic antibody endowed with a beta-lactamase activity.

Cargo binding induces dimerization of myosin VI.

Although myosin VI has properties that would allow it to function optimally as a dimer, full-length myosin VI exists as a monomer in isolation. Based on the ability of myosin VI monomers to dimerize when held in close proximity, we postulated that cargo binding normally regulates dimerization of myosin VI. We tested this hypothesis by expressing a known dimeric cargo adaptor protein of myosin VI, optineurin, and the myosin VI-binding segment from a monomeric cargo adaptor protein, Dab2.

Unregulated smooth-muscle myosin in human intestinal neoplasia.

A recent study described a recessive ATPase activating germ-line mutation in smooth-muscle myosin (smmhc/myh11) underlying the zebrafish meltdown (mlt) phenotype. The mlt zebrafish develops intestinal abnormalities reminiscent of human Peutz-Jeghers syndrome (PJS) and juvenile polyposis (JP). To examine the role of MYH11 in human intestinal neoplasia, we searched for MYH11 mutations in patients with colorectal cancer (CRC), PJS and JP.

Expression of a functional scFv fragment of an anti-idiotypic antibody with a beta-lactam hydrolytic activity.

The single chain variable fragment (scFv) of an anti-idiotypic catalytic monoclonal antibody, 9G4H9, displaying a beta-lactamase-like activity was cloned. The recombinant protein was expressed through the periplasm in Escherichia coli in the presence or in the absence of FkpA, a chaperone-like enzyme and tested for its hydrolytic activity. The results show that the catalytic parameters for hydrolysis of ampicillin by scFv9G4H9 are clearly influenced by the presence of FkpA, indicating that the correct folding of the fragment represents a crucial step for catalysis.

Folding and aggregation of export-defective mutants of the maltose-binding protein.

We previously characterized a defective-folding variant of the periplasmic maltose-binding protein, MalE31. To examine the alternative folding pathways open to the MalE31 precursor, we have analyzed the cellular fates of this aggregation-prone protein carrying altered signal sequences. Our results are most easily interpreted by a kinetic competition between exportation, folding, and degradation.