SEQUENCE OF THE PONA GENE AND CHARACTERIZATION OF THE PENICILLIN-BINDING PROTEIN 1A OF PSEUDOMONAS-AERUGINOSA PAO1

The nucleotide sequence of the ponA gene encoding the high molecular-m ass penicillin-binding protein 1A (PBP1A) of Pseudomonas aeruginosa (P a) PAO1 was determined and characterized. The predicted PBP1A protein of 822 amino acids (aa) has a calculated molecular mass of 91.2 kDa co rresponding to the size of the protein expressed in vitro and in vivo. A penicillin-binding (PB) assay showed that the Pa ponA gene product covalently binds penicillin. The deduced PBP1A aa sequence has feature s typical of class-A high-molecular-mass PBPs: a highly hydrophobic N- terminus portion containing a potential transmembrane segment which mi ght anchor the protein to the cytoplasmic membrane; an N-terminal modu le with the conserved boxes 1 (E86D(DN)F(AN)H(Y)G), 2 (G(117)GS(T)I(TM )Q), 3 (R139K(IN)E(ILL)AL) and 4 (R221R(NW)IL); a PB module with the c onserved boxes 5 (S461SFK), (S520RN) and (K(695)TG); an internal exten sion at aa 297-407 between the N-terminal and PB modules; and a C-exte nsion at the end of the PB module at aa 742 to 822. The highest percen tage of similarity (62.8% ) was found with the class A. high-molecular -mass PBP1A of Escherichia coli (Ec) and Haemophilus influenzae. The o bserved extensive homology in the modular design of the Pa PBP1A with the bifunctional Ec PBP1A suggests structural and functional relations hips between these proteins and refutes the proposed correspondence be tween Pa PBP1A and Ec PBP1B. (C) 1997 Elsevier Science B.V.