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Isolation, molecular and functional properties of the C‐terminal domain of colicin A.
Author(s) -
Martinez M.C.,
Lazdunski C.,
Pattus F.
Publication year - 1983
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1983.tb01614.x
Subject(s) - biology , colicin , terminal (telecommunication) , isolation (microbiology) , domain (mathematical analysis) , computational biology , genetics , evolutionary biology , bioinformatics , dna , plasmid , telecommunications , mathematical analysis , mathematics , computer science
Partial proteolytic digestion of colicin A with bromelain allowed the isolation of a 20‐kd fragment. This fragment has been purified to homogeneity and its molecular properties have been studied. The sequence of the 54 N‐terminal amino acid residues has been determined by automated Edman degradation. This sequence is identical to that of the predicted amino acid sequence of the 20‐kd C‐terminal part of the colicin A polypeptide deduced from the nucleotide sequence of the caa gene. This polypeptide can produce channels in phospholipid planar bilayers of the same size as those formed by colicin A. However, the voltage‐dependence for opening and closing was drastically altered in the peptide fragment channels. The latter, in contrast to colicin A channels, remained open over a wide range of voltage. Large negative potentials were required to close the peptide fragment channels although opening took place in the same voltage range as for colicin A ionic pores.