LITHOSTATHINE, AN INHIBITOR OF CACO3 CRYSTAL-GROWTH IN PANCREATIC-JUICE, INDUCES BACTERIAL AGGREGATION

Lithostathine is a pancreatic secretory protein which controls CaCO3 c rystal growth in pancreatic juice. Trypsin hydrolysis of the molecule generates two fragments of 11 and 133 amino acids. The N-terminal unde capeptide bears the inhibitory activity for crystal growth. We demonst rate that the C-terminal part of the molecule, which is structurally r elated to Ca2+-dependent lectins, can induce bacterial aggregation. Ca 2+- and pH-dependent aggregation was obtained for Escherichia coli str ain KH 802 and 9 of 19 strains isolated from the predominant flora of human feces. Aggregation of E. coli could be reversed by dilution and bacteria could resume normal growth. Lithostathine is apparently the o nly component of normal pancreatic juice displaying such activity. Lit hostathine is therefore a bifunctional protein which might be involved in the control of the bacterial ecosystem in the intestine.