Key events during the transition from rapid growth to quiescence in budding yeast require posttranscriptional regulators.

Publication Type:

Journal Article

Source:

Molecular biology of the cell, Volume 24, Issue 23, p.3697-709 (2013)

Keywords:

2013, Basic Sciences Division, Center-Authored Paper, Computational Biology Core Facility, Flow Cytometry Core Facility, Genomics Core Facility, October 2013

Abstract:

Yeast that naturally exhaust the glucose from their environment differentiate into three distinct cell types distinguishable by flow cytometry. Among these is a quiescent (Q) population, which is so named because of its uniform but readily reversed G1 arrest, its fortified cell walls, heat tolerance and longevity. Daughter cells predominate in Q cell populations and are the longest-lived. The events that differentiate Q cells from non-quiescent (nonQ) cells are initiated within hours of the diauxic shift, when cells have scavenged all the glucose from the media. These include highly asymmetric cell divisions, which gives rise to very small daughter cells. These daughters modify their cell walls by Sed1-, Ecm33-dependent, and dithiothreitol-sensitive mechanisms which enhance Q cell thermo-tolerance. Ssd1 speeds Q cell wall assembly and enables mother cells to enter this state. Ssd1 and the related mRNA binding protein Mpt5 play critical overlapping roles in Q cell formation and longevity. These proteins deliver mRNAs to P-bodies and at least one P-body component, Lsm1 also plays a unique role in Q cell longevity. Cells lacking Lsm1, and Ssd1 or Mpt5 lose viability under these conditions and fail to enter the quiescent state. We conclude that posttranscriptional regulation of mRNAs plays a crucial role in the transition in and out of quiescence.