MsJ1, an alfalfa DnaJ-like gene, is tissue-specific and transcriptionally regulated during cell cycle

DnaJ-like proteins are molecular chaperones that regulate Hsp70 ATPase acti vity both in protein folding, assembly and disassembly of protein complexes . Here we report the isolation of MsJ1, an alfalfa gene encoding a protein homologous to cytosolic DnaJ-like proteins. MsJ1 was induced under heat-sho ck treatment in both leaves and stems of adult plants. In the absence of he at shock MsJ1 expression was tissue-specific with the highest levels of mRN A in roots and in embryonal structures. High levels of transcript were also detected in cotyledons where active degradation of storage protein occurs. In synchronized alfalfa suspension-cultured cells the MsJ1 transcript was actively expressed and showed a phase-specific modulation during cell cycle with a 2-fold induction in G2/M. These findings suggest that DnaJ-like pro teins play an active role in regulating normal cellular events like protein degradation, morphogenesis and cell cycle progression.