The gene encoding the metacyclogenesis-associated transcript Mat-1 is conserved in the genus Leishmania and shows a tendency to form dimers upon protein expression

The Leishmania infantum Mat-1 gene - recently described in L. major as a hi ghly stage-specific, metacyclogenesis-associated transcript - has been clon ed. The 420-bp Mat-1 coding region is conserved with respect to the L. majo r gene (82% sequence homology). Analysis of the predicted amino-acid sequen ce reveals structural motifs showing homology with the class of leucine-zip per transcription factors. Southern-blot hybridization analysis suggests th at Mat-1 is a low-copy-number gene, probably consisting of two gene copies. The recombinant Mat-1 protein expressed in fusion with the Escherichia col i maltose-binding protein shows a tendency to form dimers in the presence o f the leucine-rich C-terminal domain. Bacteria expressing the Mat-1 open re ading frame are highly growth-attenuated and tend to delete or modify the i nsert, which suggests that expression of Mat-1 is toxic for the bacteria.