Article

Crystal Structure of Alkaline Protease from Pseudomonas Aeruginosa IFO3455

01/1994;
Source: OAI

ABSTRACT structure of alkaline protease from Pseudomonas aeruginosa IF03455, a zinc- requiring metalloprotease, has been determined by a multiple isomorphous replacement method of X-ray crystallography, and refined at 2.3 A resolution to the R-factor of 0.198. The molecule has an elongated ellipsoidal shape with approximate dimensions of 90 X 42 X 35 A. It consists of two distinct structural domains. The N-terminal domain is the proteolytic domain which contains the active site zinc atom in the inside of the large cleft. The overall structure of the domain is similar to that of astacin, a metalloprotease belonging to a superfamily different from that of the alkaline protease. The C-terminal domain has a two- layer /3-sandwich structure consisting of 19 /3-strands. In the central region of this domain is an unusual parallel /3-helix structure in which successive /3-strands are wound in a right-handed spiral through the short turns between the strands. Ca2+ ions bound internally within the turns formed by a repeated GGXGXD sequence motif may play an essential role in stabilizing this /3-helix structure. Alkaline protease from Pseudomonas aeruginosa IF03455 is a zinc-requiring metalloendo- protease consisting of 470 amino acid residues 1'2) with one catalytic zinc atom.3-4) Biochemical studies on the alkaline protease have revealed that the enzyme possesses a relatively wide specificity for substrates, and that the potential catalytic capability is optimized at pH 8 to 10,5-6) which is unusual compared with other metalloendoproteases such as thermolysin, subtilisins, and neutral endopeptidases which are neutral in optimal pH. The pathologic aspects of the P. aeruginosa alkaline protease have been extensively investigated so far. The enzyme possesses potential anti-coagulant capacity to hydrolyze natural substrates of plasmin, such as fibrin and fibrinogen, with similar specific activities to plasmin.7) From these properties of the enzyme, it is inferred that the P. aeruginosa alkaline protease may play a key role in infection of the bacteria to their host cells through inactivation of various physiological activators such as some complement components, immunoglobulins A and G, and many protease inhibitors.$) Zinc-requring

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May 22, 2014