Sl. Chiang et al., SINGLE AMINO-ACID SUBSTITUTIONS IN THE N-TERMINUS OF VIBRIO-CHOLERAE TCPA AFFECT COLONIZATION, AUTOAGGLUTINATION, AND SERUM RESISTANCE, Molecular microbiology, 17(6), 1995, pp. 1133-1142
The toxin-coregulated pilus (TCP) of Vibrio cholerae O1 is required fo
r successful infection of the host. TcpA, the structural subunit of TC
P, belongs to the type IV family of pilins, which includes the PilE pi
lin of Neisseria gonorrhoeae. Recently, single amino acid changes in t
he N-terminus of PilE were found to abolish autoagglutination in gonoc
occi. As type IV pilins demonstrate some similarities in function and
amino acid sequence, site-directed mutagenesis and allelic exchange we
re used to create corresponding mutations in TcpA. All four mutant str
ains demonstrated autoagglutination defects, and all were highly defec
tive for colonization in the infant mouse model. These results support
the previously proposed correlation between autoagglutination and col
onization. Finally, all four mutants are serum sensitive, indicating t
hat TcpA plays a role in serum resistance, a phenotype previously attr
ibuted to TcpC. As the mutations have similar effects in N. gonorrhoea
e and V. cholerae, our results support the idea that type IV pilins ha
ve similar functions in a variety of pathogenic bacteria.