FUNCTIONAL INTERACTION BETWEEN caf5 AND SPERMIDINE FAMILY TRANSPORTERS IN S. POMBE

Abstract

Polyamines are well known for their wide range of roles in the cells, including stabilization of nucleic acids, regulation of geneexpression at different levels, stress response and cell cycle. The activity of these well conserved small polycations are alsoregulated by different mechanisms to assure their intracellular concentration and activity. Polyamine transporters have a majorrole in the regulation of the influx and efflux of the polyamines. Previously, two spermine family transporters SPBC409.08 andcaf5 were characterized which were associated with cell size defects. The aim of this study is to better understand the role ofcaf5 plasma membrane spermine transporter and its functional interaction with spermidine transporters. Double mutants ofcaf5 and spermidine family transporters SPBC36.01c, SPBC36.03c and SPBC569.05c were formed in S. pombe. The doublemutants were then put through growth rate analysis, meiotic progression and sporulation analysis, cell cycle analysis, andvulnerability to environmental stress. The results showed that the double mutants differentiate from each other in theircombined mutation with caf5 in terms of cell size and DNA damage response, indicating redundant seperate pathways ofspermine and spermidine transport in S. pombe.