Determination of the gene sequence and the molecular structure of the enterococcal peptide antibiotic AS-48.
The structural gene of the enterococcal peptide antibiotic AS-48 (as-48) has been identified and cloned by using two degenerate 17-mer DNA oligonucleotides on the basis of the amino acid sequences of two peptides obtained by digestion of the antibiotic with Glu-C endoproteinase. That as-48 gene codes for a 105-amino-acid prepeptide, giving rise to a 70-amino-acid mature protein. Comparative analysis demonstrated that the 16-amino-acid sequence of one of the AS-48 Glu-C peptides, designated V8-5, was composed of a 12-amino-acid sequence corresponding to the C-terminal end sequence (from isoleucine +59 to tryptophan +70 [I+59 to W+70]) of the prepeptide and terminated in four residues forming the N terminus (M+1 to E+4) of a putative AS-48 propeptide. These data, combined with the characteristics of the gene sequence, strongly suggested that the antibiotic peptide was a 70-residue cyclic molecule. We propose that the AS-48 translated primary product is very likely submitted to a posttranslational modification during secretion (i) by an atypical or a typical signal peptidase that cleaves off a 35-residue or shorter signal peptide, respectively, from the prepeptide molecule and (ii) by the linkage of the methionine residue (M+1) to the C-terminal tryptophan residue (W+70) to obtain the cyclic peptide (a tail-head linkage).
Martínez-Bueno
M
M
Centre d'Ingénierie des Protéines, Institut de Chimie B6, Université de Liège, Sart Tilman, Belgium.
Maqueda
M
M
Gálvez
A
A
Samyn
B
B
Van Beeumen
J
J
Coyette
J
J
Valdivia
E
E
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry; D001426:Bacterial Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D016983:Enterococcus / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides; D010456:Peptides, Cyclic / Q000737:chemistry / Q000235:genetics*; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D017421:Sequence Analysis
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D010446:Peptide Fragments; D010455:Peptides; D010456:Peptides, Cyclic; C051034:BacA protein, Enterococcus faecalis