Affiliation:
1. Department of Pathology and WHO Collaborating Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas 77555-0609
Abstract
ABSTRACT
The glycoprotein genes of
Ehrlichia chaffeensis
(1,644 bp) and
Ehrlichia canis
(2,064 bp) encode proteins of 548 to 688 amino acids with predicted molecular masses of only 61 and 73 kDa but with electrophoretic mobilities of 120 kDa (P120) and 140 kDa (P140), respectively. The 120-kDa protein gene of
E. chaffeensis
contains four identical 240-bp tandem repeat units, and the 140-kDa protein gene of
E. canis
has 14 nearly identical, tandemly arranged 108-bp repeat units. Conserved serine-rich motifs identified in the repeat units of P120 and P140 were also found in the repeat units of the human granulocytotropic ehrlichiosis agent 130-kDa protein and of the fimbria-associated adhesin protein Fap1 of
Streptococcus parasanguis
. Nearly the entire (99%)
E. chaffeensis
P120 gene (1,616 bp), the 14-repeat region (78%) of the
E. canis
P140 gene (1,620 bp), and a 2-repeat region from the
E. chaffeensis
P120 gene (520 bp) were expressed in
Escherichia coli
. The recombinant proteins exhibited molecular masses ranging from 1.6 to 2 times larger than those predicted by the amino acid sequences. Antibodies against the recombinant proteins reacted with
E. chaffeensis
P120 and
E. canis
P140, respectively. Carbohydrate was detected on the
E. chaffeensis
and
E. canis
recombinant proteins, including the two-repeat polypeptide region of
E. chaffeensis
P120. A carbohydrate compositional analysis identified glucose, galactose, and xylose on the recombinant proteins. The presence of only one site for N-linked (Asn-Xaa-Ser/Thr) glycosylation, a lack of effect of
N
-glycosidase F, the presence of 70 and 126 Ser/Thr glycosylation sites in the repeat regions of P120 and P140, respectively, and a high molar ratio of carbohydrate to protein suggest that the glycans may be O linked.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
59 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献