Isolation and molecular and functional properties of the amino-terminal domain of colicin A |
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Authors: | M Knibiehler S P Howard D Baty V Geli R Lloubès P Sauve C Lazdunski |
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Institution: | Centre de Biochimie et de Biologie Moléculaire du Centre National de la Recherche Scientifique, Marseille, France. |
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Abstract: | A plasmid was constructed which allowed easy and efficient production and purification of the NH2-terminal domain of colicin A. In only three steps, an homogenous 18-kDa polypeptide was obtained. The NH2- and COOH-terminal sequences of the protein were determined and showed that it corresponded to the NH2-terminal 171 amino acid residues of the 63-kDa colicin A. Although colicin A is a highly asymmetric protein, hydrodynamic studies indicated that the NH2-terminal domain (designated AT) has a globular structure. This fragment is not the receptor-binding domain of colicin A but is required for the transfer of colicin A across the outer membrane of sensitive cells. However, it has a low affinity for phospholipid films and this affinity is not pH-dependent, in contrast to that of colicin A. |
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