Heme-mediated transcriptional control in Kluyveromyces lactis

Heme is of great importance in oxygen-dependent biological functions, since it serves as a prosthetic group for many proteins related to oxygen-bindin g, oxidative damage prevention and electron transport. It also regulates ge ne expression through the action of specific transcriptional regulatory fac tors. In this paper, we present an analysis of heme-dependent transcription al regulation of several respiration-related genes in an aerobic respirator y yeast, Kluyveromyces,ces lactis. We also report that the KlHEM13 gene, en coding the heme biosynthetic enzyme coproporphyrinogen oxidase, is under he me and oxygen transcriptional regulation, thereby controlling the synthesis of the effector, heme. KlHEM13 is induced during hypoxia, which represents the first report of a transcriptionally regulated gene with this behaviour in K. lactis.