Monospecific polyclonal antisera raised against Rhizobium leguminosarum bv. trifolii R39, a bacterium which was isolated originally from red clover nodules, were used to study the colonization of roots of leguminous and nonleguminous plants (Pisum sativum, Lupinus albus, Triticúm aestivum, and Zea mays) after inoculation. Eight weeks after inoculation of soil-grown plants, between 0.1 and 1% of...

Streptomyces albus G secretes a Zn2+-containing D-alanyl-D-alanine peptidase. Streptomyces R61 and Actinomadura R39 secrete D-alanyl-D-alanine-cleaving serine peptidases. The effect of non-classical beta-lactam antibiotics on these three model enzymes has been studied. Mecillinam, cefoxitin, quinacillin, quinacillin sulphone, clavulanate and N-formimidoylthienamycin have no effect on the Zn2+-c...

6-Beta-halogenopenicillanates are powerful, irreversible inhibitors of various beta-lactamases and penicillin-binding proteins. Upon acylation of these enzymes, the inhibitors are thought to undergo a structural rearrangement associated with the departure of the iodide and formation of a dihydrothiazine ring, but, to date, no structural evidence has proven this. 6-Beta-iodopenicillanic acid (BI...

By using the promoter-probe plasmid pIJ424, genomic DNA fragments of Actinomadura R39 were shown to have promoter activity in Streptomyces lividans. The same 100-200-copy-number plasmid was used to clone in S. lividans TK24, the gene that encodes the Actinomadura R39 beta-lactamase. Gene cloning resulted in an amplified expression of the beta-lactamase when compared with the amounts of enzyme p...

Since the discovery of penicillin, bacteria have counteracted the action of antibiotics leading to a worrisome situation about antibiotic efficiency. During our research on non-traditional 1,3-bridged b-lactams embedded into macrocycles as potential inhibitors of Penicillin Binding Proteins (PBPs), we unexpectedly synthesized bis-2-oxoazetidinyl macrocycles arising from a dimerization reaction ...

Actinomadura sp. R39 produces an exocellular DD-peptidase/penicillin-binding protein (PBP) whose primary structure is similar to that of Escherichia coli PBP4. It is characterized by a high beta-lactam-binding activity (second order rate constant for the acylation of the active site serine by benzylpenicillin: k2/K = 300 mm(-1) s(-1)). The crystal structure of the DD-peptidase from Actinomadura...

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 exclude...

The 29,000-Mr Actinomadura R39 beta-lactamase exhibited a remarkably low electrophoretic mobility on SDS/PAGE, yielding an Mr value almost twice that computed from the corresponding gene sequence. We showed that chemical modification of the carboxylic groups of glutamic acid and aspartic acid residues restored a normal electrophoretic mobility and that the anomalous behaviour of that protein on...

The X-ray crystal structures of covalent complexes of the Actinomadura R39 dd-peptidase and Escherichia coli penicillin-binding protein (PBP) 5 with beta-lactams bearing peptidoglycan-mimetic side chains have been determined. The structure of the hydrolysis product of an analogous peptide bound noncovalently to the former enzyme has also been obtained. The R39 DD-peptidase structures reveal the...

The ability of the water-soluble DD-carboxypeptidases of Streptomyces strains albus G, R61, Kll and R39 to perform transpeptidation was studied. The donor was diacetylL-lysyl-D-alanyl-D-alanine, and a whole range of amino acids, peptides and structurally related amino compounds were tested for acceptor function. No compound tested was an acceptor for the enzyme from strain albus G whereas the e...