Domain structure of CAF1M protein from Yersinia pestis. Structure and the role of various domains

The cooperative structure of Caf1M from Yersinia pestis was studied using scanning microcalorimetry, fluorescence, and limited proteolysis. It was shown that, in Caf1M-Hg (a derivative in which the disulfide bond is replaced by an S-Hg-S bond), the first to melt is the N-domain. Then the C-domain melts. After renaturation in a buffer with a low NaCl concentration, only the C-domain is in the native state, and it can be obtained by limited proteolysis. After renaturation in a buffer with a high NaCl concentration, only the N-domain is in the native state, and it can be obtained by limited proteolysis. Both domains have native structure; however, only the N-domain interacts with Cafl (natural substrate for Caf1M).