PubMed Health⌕ Search

Biomedical subjects

B Granier

Publications and source records attributed to B Granier.

11 recordsLinked to original sources
PubMed1994

The precursor of the Streptomyces R61 DD-peptidase containing a C-terminal extension is inactive.

The Streptomyces R61 DD-peptidase gene encodes a 26-residue C-terminal extension which is not found in the mature protein. When the gene was expressed in Escherichia coli, the extension was not cleaved and the precursor protein was not enzymatically active. It also reacted with penicillins significantly more slowly than the mature protein. The introduction of a 'stop' codon after that corresponding to the C-terminal residue of the mature protein resulted in the production of an active protein in the periplasm of E. coli.

Amino Acid Sequence↗
PubMed1994

Engineering and overexpression of periplasmic forms of the penicillin-binding protein 3 of Escherichia coli.

Replacement of the 36 and 56 N-terminal amino acid residues of the 588-amino-acid-residue membrane-bound penicillin-binding protein 3 (PBP3) of Escherichia coli by the OmpA signal peptide allows export of F37-V577 PBP3 and G57-V577 PBP3 respectively into the periplasm. The modified ftsI genes were placed under the control of the fused lpp promoter and lac promoter/operator; expression of the truncated PBP3s was optimized by varying the copy number of the recombinant plasmids and the amount of LacI repressor, and export was facilitated by increasing the SecB content of the producing strain. The periplasmic PBP3s (yield 8 mg/l of culture) were purified to 70% protein homogeneity. They require the presence of 0.25 M NaCl to remain soluble. Like the membrane-bound PBP3, they undergo processing by elimination of the C-terminal decapeptide I578-S588, they bind penicillin in a 1:1 molar ratio and they catalyse hydrolysis and aminolysis of acyclic thioesters that are analogues of penicillin. The membrane-anchor-free PBP3s have ragged N-termini. The G57-V577 PBP3, however, is less prone to proteolytic degradation than the F37-V577 PBP3.

Amino Acid Sequence↗
PubMed1992

Primary and predicted secondary structures of the Actinomadura R39 extracellular DD-peptidase, a penicillin-binding protein (PBP) related to the Escherichia coli PBP4.

As derived from gene cloning and sequencing, the 489-amino-acid DD-peptidase/penicillin-binding protein (PBP) produced by Actinomadura R39 has a primary structure very similar to that of the Escherichia coli PBP4 [Mottl, Terpstra & Keck (1991) FEMS Microbiol. Lett. 78, 213-220]. Hydrophobic-cluster analysis of the two proteins shows that, providing that a large 174-amino-acid stretch is excluded from the analysis, the bulk of the two polypeptide chains possesses homologues of the active-site motifs and secondary structures found in the class A beta-lactamase of Streptomyces albus G of known three-dimensional structure. The 174-amino-acid insert occurs at equivalent places in the two PBPs, between helices alpha 2 and alpha 3, away from the active site. Such an insert is unique among the penicilloyl serine transferases. It is proposed that the Actinomadura R39 PBP and E. coli PBP4 form a special class, class C, of low-Mr PBPs/DD-peptidases. A vector has been constructed and introduced by electrotransformation in the original Actinomadura R39 strain, allowing high-level expression and secretion of the DD-peptidase/PBP (250 mg.l-1). The gene encoding the desired protein is processed differently in Actinomadura R39 and Streptomyces lividans. Incorrect processing in Streptomyces lividans leads to a secreted protein which is inert in terms of DD-peptidase activity and penicillin-binding capacity.

Actinomycetales↗
PubMed1990

The diversity of the catalytic properties of class A beta-lactamases.

The catalytic properties of four class A beta-lactamases were studied with 24 different substrates. They exhibit a wide range of variation. Similarly, the amino acid sequences are also quite different. However, no relationships were found between the sequence similarities and the substrate profiles. Lags and bursts were observed with various compounds containing a large sterically hindered side chain. As a group, the enzymes could be distinguished from the class C beta-lactamases on the basis of the kappa cat. values for several substrates, particularly oxacillin, cloxacillin and carbenicillin. Surprisingly, that distinction was impossible with the kappa cat./Km values, which represent the rates of acylation of the active-site serine residue by the beta-lactam. For several cephalosporin substrates (e.g. cefuroxime and cefotaxime) class A enzymes consistently exhibited higher kappa cat. values than class C enzymes, thus belying the usual distinction between 'penicillinases' and 'cephalosporinases'. The problem of the repartition of class A beta-lactamases into sub-classes is discussed.

Amino Acid Sequence↗
PubMed1989

[Complications of transurethral resection in the treatment of benign prostatic hypertrophy. Apropos of a series of 1180 adenomas--1976-1986].

This was a homogeneous series treated by the same surgeon between January 1977 and December 1986. During this period, out of 1,806 certico-prostatic obstacles, 1,180 were treated by resection of a prostatic adenoma with a mean age of 68,3 years and a range of 37 to 94 years. The surgical indications fell into four groups: dominant dysuria, dominant pollakiuria, complicated adenomas and patients with a single past episode of acute urinary retention. Resection was performed with a direct current (Iglésias) essentially with sterile demineralized water. General anesthesia was used in 2/3 of the cases and loco-regional anesthesia in 1/3 of the cases. A traditional resection technique was used, and postoperative bladder drainage used a Mercier 24 catheter. Continuous lavage was not performed. Duration of resection was 10 to 120 minutes with a mean of 39 minutes. The resected weight ranged between 8 and 130 grams with a mean of 24.2 grams. Duration of the indwelling catheter decreased from 5 days in 1976 to 24 or 48 hours in 1982. Duration of hospitalization decreased from 12 to 7 days, and down to 5 days today. Complications were uncommon: 2 deaths (0.17%) due to acute pancreatitis and mesenteric infarction; 1 perforated bladder; 4 septicemia with shock; 2 acute renal failures requiring dialysis; 5 pulmonary emboli; 3 hemiplegia; 1 acute nonfatal pancreatitis. Only 50 patients (4.2%) required transfusions. There was no permanent urinary incontinence but there were 12 (0.1%) cervical stenoses, and 37 (3.13%) urethral stenoses. Five-hundred-and-fifty-two patients were followed for one year and more: the results were overall very good.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMedDate not supplied

Diversity of the mechanisms of resistance to beta-lactam antibiotics.

The sensitivity of a bacterium to beta-lactam antibiotics depends upon the interplay between 3 independent factors: the sensitivity of the essential penicillin-binding enzyme(s), the quantity and properties of the beta-lactamase(s) and the diffusion barrier that the outer-membrane of Gram-negative bacteria can represent. Those three factors can be modified by mutations or by the horizontal transfer of genes or portions of genes.

Anti-Bacterial Agents↗