title: The Rim101p/PacC pathway and alkaline pH regulate pattern formation in yeast colonies.
abstract: Multicellular organisms utilize cell-to-cell signals to build patterns of cell types within embryos, but the ability of fungi to form organized communities has been largely unexplored. Here we report that colonies of the yeast Saccharomyces cerevisiae formed sharply divided layers of sporulating and nonsporulating cells. Sporulation initiated in the colony's interior, and this region expanded upward as the colony matured. Two key activators of sporulation, IME1 and IME2, were initially transcribed in overlapping regions of the colony, and this overlap corresponded to the initial sporulation region. The development of colony sporulation patterns depended on cell-to-cell signals, as demonstrated by chimeric colonies, which contain a mixture of two strains. One such signal is alkaline pH, mediated through the Rim101p/PacC pathway. Meiotic-arrest mutants that increased alkali production stimulated expression of an early meiotic gene in neighboring cells, whereas a mutant that decreased alkali production (cit1Delta) decreased this expression. Addition of alkali to colonies accelerated the expansion of the interior region of sporulation, whereas inactivation of the Rim101p pathway inhibited this expansion. Thus, the Rim101 pathway mediates colony patterning by responding to cell-to-cell pH signals. Cell-to-cell signals coupled with nutrient gradients may allow efficient spore formation and spore dispersal in natural environments.
authors.affiliation: Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri, Kansas City, Missouri 64110, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Piccirillo
authors.forename: Melissa G
authors.initials: MG
authors.lastname: White
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Murphy
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Law
authors.forename: Saul M
authors.initials: SM
authors.lastname: Honigberg
mesh_terms: D002450:Cell Communication / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008540:Meiosis / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013172:Spores, Fungal / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: C080326:IME1 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; C489601:RIM101 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C064979:IME2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases