MOLECULAR-CLONING AND NUCLEOTIDE-SEQUENCE ANALYSIS OF THE MALTOSE-INDUCIBLE PORIN GENE OF AEROMONAS-SALMONICIDA

The gene for the Aeromonas salmonicida maltose-inducible porin (maltop orin) was cloned into phagemid pTZ18R in two restriction fragments, 0. 6-kb PstI/KpnI and 1.7-kb SphI, of genomic DNA and their nucleotide se quences were determined. Open reading frames of 1329 and 1335 bp trans lated into sequences of 443 and 445 amino acids, with a 23 or 25 amino acid signal sequence and a 420 amino acid mature protein of molecular mass 46424 Da. Putative ribosome binding sites, AGGA and GGGAA, occur red 9 bp upstream of two possible ATG initiation codons. The A. salmon icida gene product showed a high degree of similarity with Escherichia coli LamB, and codon usage was very similar to that of another A. sal monicida outer membrane protein but markedly different from those of e xtracellular proteins.