Molecular characterization of KEX1, a kexin-like protease in mouse Pneumocystis carinii.
Expression screening of a Pneumocystis carinii-infected mouse lung cDNA library with specific monoclonal antibodies (mAbs) led to the identification of a P. carinii cDNA with extensive homology to subtilisin-like proteases, particularly fungal kexins and mammalian prohormone convertases. The 3.1 kb cDNA contains a single open reading frame encoding 1011 amino acids. Structural similarities to fungal kexins in the deduced primary amino acid sequence include a putative proenzyme domain delineated by a consensus autocatalytic cleavage site (Arg-Glu-Lys-Arg), conserved Asp, His, Asn and Ser residues in the putative catalytic domain, a hydrophobic transmembrane spanning domain, and a carboxy-terminal cytoplasmic domain with a conserved tyrosine motif thought to be important for localization of the protease in the endoplasmic reticulum and/or Golgi apparatus. Based on these structural similarities and the classification of P. carinii as a fungus, the protease was named KEX1. Southern blotting of mouse P. carinii chromosomes localized kex1 to a single chromosome of approximately 610 kb. Southern blotting of restriction enzyme digests of genomic DNA from P. carinii-infected mouse lung demonstrated that kex1 is a single copy gene. The function of kexins in other fungi suggests that KEX1 may be involved in the post-translational processing and maturation of other P. carinii proteins.
Lee
L H
LH
Department of Pediatrics, University of Rochester School of Medicine and Dentistry, NY 14642, USA.
Gigliotti
F
F
Wright
T W
TW
Simpson-Haidaris
P J
PJ
Weinberg
G A
GA
Haidaris
C G
CG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002268:Carboxypeptidases / Q000235:genetics*; D015825:Chromosomes, Fungal / Q000235:genetics; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D008168:Lung / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D008969:Molecular Sequence Data; D011010:Pneumocystis / Q000235:genetics*; D043484:Proprotein Convertases; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013381:Subtilisins / Q000235:genetics*
D018076:DNA, Complementary; D004271:DNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D002268:Carboxypeptidases; C078874:carboxypeptidase D; D043484:Proprotein Convertases; D013381:Subtilisins; C058751:KEX2 protein, S cerevisiae