About

Keith Kozminski is an Associate Professor of Biology and Cell Biology and serves as the Director of Undergraduate Programs at the University of Virginia. He holds a B.A. and B.S. from the State University of New York, Buffalo, obtained in 1989, and a Ph.D. from Yale University, completed in 1995. His postdoctoral research was conducted at the University of California, Berkeley, from 1995 to 2001. His current research focuses on the molecular mechanisms that regulate asymmetric or polarized cell growth, using the budding of the yeast Saccharomyces cerevisiae as an experimental model. This model is significant because many organisms depend on polarized cell growth for cellular functions and development, and understanding these processes in yeast provides insights into more complex eukaryotic cells, including human cells. His work aims to decipher how processes such as the selection of growth sites, establishment of polarity axes, and polarized exocytosis are interconnected and regulated by diffusible molecules. His research emphasizes the importance of polarized cell growth in development, tissue function, and cell division, and explores how defects in these processes can lead to organismal death or failure. Kozminski's lab investigates key questions such as how cells maintain sufficient concentrations of activated Cdc42p at growth sites, the molecular links between polarized exocytosis and cell cycle progression, and the regulatory roles of lipid-binding proteins like oxysterol binding proteins in polarized exocytosis and growth. His work leverages the genetic and molecular biology advantages of yeast to understand these complex cellular processes, with broader implications for synthetic biology and engineering.

Research topics

• Cell biology
• Biology
• Biochemistry

Selected publications

• Osh-dependent and -independent Regulation of PI4P Levels During Polarized Growth of<i>Saccharomyces cerevisiae</i>

  Molecular Biology of the Cell · 2023 · 2 citations

  Senior authorCorresponding
  • Biology
  • Cell biology
  • Biochemistry

  family function alters the intracellular distribution of PI4P. We propose a model in which the Rab GTPases Ypt32p and Sec4p remain associated with a secretory vesicle during trafficking, independent of PI4P levels and Osh4p. Together these data indicate the necessity of experiments revealing the location and timing of events required for vesicle maturation.

  PublisherOA PDFDOI

• Functions for Cdc42p BEM adaptors in regulating a differentiation-type MAP kinase pathway

  Molecular Biology of the Cell · 2020 · 22 citations

  • Biology
  • Cell biology

  , that is specifically defective for fMAPK pathway signaling, was defective for interaction with Bem4p, the pathway-specific adaptor for the fMAPK pathway. Corresponding residues in Bem4p were identified that were required for interaction with Cdc42p and fMAPK pathway signaling. The polarity adaptor Bem1p also regulated the fMAPK pathway. Versions of Bem1p defective for recruitment of Ste20p to the plasma membrane, intramolecular interactions, and interaction with the GEF, Cdc24p, were defective for fMAPK pathway signaling. Bem1p also regulated effector pathways in different ways. In some pathways, multiple domains of the protein were required for its function, whereas in other pathways, a single domain or function was needed. Genetic suppression tests showed that Bem4p and Bem1p regulate the fMAPK pathway in an ordered sequence. Collectively, the study demonstrates unique and sequential functions for Rho GTPase adaptors in regulating MAPK pathways.

  PublisherOA PDFDOI

• A protein interaction map for cell polarity development

  UNC Libraries · 2020-10-31

  articleOpen access

  Many genes required for cell polarity development in budding yeast have been identified and arranged into a functional hierarchy. Core elements of the hierarchy are widely conserved, underlying cell polarity development in diverse eukaryotes. To enumerate more fully the protein–protein interactions that mediate cell polarity development, and to uncover novel mechanisms that coordinate the numerous events involved, we carried out a large-scale two-hybrid experiment. 68 Gal4 DNA binding domain fusions of yeast proteins associated with the actin cytoskeleton, septins, the secretory apparatus, and Rho-type GTPases were used to screen an array of yeast transformants that express ∼90% of the predicted Saccharomyces cerevisiae open reading frames as Gal4 activation domain fusions. 191 protein–protein interactions were detected, of which 128 had not been described previously. 44 interactions implicated 20 previously uncharacterized proteins in cell polarity development. Further insights into possible roles of 13 of these proteins were revealed by their multiple two-hybrid interactions and by subcellular localization. Included in the interaction network were associations of Cdc42 and Rho1 pathways with proteins involved in exocytosis, septin organization, actin assembly, microtubule organization, autophagy, cytokinesis, and cell wall synthesis. Other interactions suggested direct connections between Rho1- and Cdc42-regulated pathways; the secretory apparatus and regulators of polarity establishment; actin assembly and the morphogenesis checkpoint; and the exocytic and endocytic machinery. In total, a network of interactions that provide an integrated response of signaling proteins, the cytoskeleton, and organelles to the spatial cues that direct polarity development was revealed.

  PublisherDOI

• Functions for Cdc42p BEM Adaptors in Regulating a Differentiation-Type MAP Kinase Pathway

  bioRxiv (Cold Spring Harbor Laboratory) · 2019-09-30

  preprintOpen access

  ABSTRACT Rho GTPases regulate cell polarity and signal transduction pathways to control morphogenetic responses in different settings. In yeast, the Rho GTPase Cdc42p regulates cell polarity, and through the p21-activated kinase Ste20p, Cdc42p also regulates mitogen-activated protein kinase (MAPK) pathways (mating, filamentous growth or fMAPK, and HOG). Although much is known about how Cdc42p regulates cell polarity and the mating pathway, how Cdc42p regulates the fMAPK pathway is not clear. To address this question, Cdc42p-dependent MAPK pathways were compared in the filamentous (∑1278b) strain background. Each MAPK pathway showed a unique activation profile, with the fMAPK pathway exhibiting slow activation kinetics compared to the mating and HOG pathways. A previously characterized version of Cdc42p, Cdc42p E100A , that is specifically defective for fMAPK pathway signaling, was defective for interaction with Bem4p, the pathway-specific adaptor for the fMAPK pathway. Corresponding residues in Bem4p were identified that were required for interaction with Cdc42p and fMAPK pathway signaling. The polarity adaptor Bem1p also regulated the fMAPK pathway. In the fMAPK pathway, Bem1p recruited Ste20p to the plasma membrane, cycled between an open and closed conformation, and interacted with the GEF for Cdc42, Cdc24p. Bem1p also regulated effector pathways in different ways, behaving as a multi-functional adaptor in some pathways and an inert scaffold in others. Genetic suppression tests showed that Bem4p and Bem1p regulate the fMAPK pathway in an ordered sequence. Collectively, the study demonstrates unique and sequential functions for Rho GTPase adaptors in regulating MAPK pathways. HIGHLIGHTS Comparing Cdc42p-dependent MAPK pathways showed that the fMAPK pathway had slow activation kinetics compared to the mating and HOG pathways. A collection of cdc42 alleles was tested for MAPK pathway functions. § Cdc42p E100A , previously characterized as being specifically defective for fMAPK signaling, showed reduced interaction with the fMAPK pathway adaptor Bem4p. § Corresponding residues in Bem4p were identified that were required for interaction with Cdc42p and fMAPK signaling. The polarity adaptor Bem1p regulated the fMAPK pathway. § Bem1p regulated the fMAPK pathway by recruiting Ste20p to the plasma membrane, cycling between an open and closed conformation, and interacting with the Cdc42p GEF, Cdc24p. Different domains of Bem1p had different roles in regulating effector pathways. § Bem1p may function as a multi-functional adaptor in some pathways and an inert scaffold in others. Bem4p and Bem1p regulated the fMAPK pathway in an ordered sequence. § The data support a model where Bem4p recruits Cdc24p to GDP-Cdc42p, and Bem1p directs GTP-Cdc42p to Ste20p at the plasma membrane. § The bud-site GTPase Rsr1p regulates Cdc24p in the fMAPK pathway but does not initiate signaling.

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• Lipid-dependent regulation of exocytosis in <i>S. cerevisiae</i> by OSBP homolog (Osh) 4

  Journal of Cell Science · 2017-10-10 · 23 citations

  articleSenior author

  ABSTRACT Polarized exocytosis is an essential process in many organisms and cell types for correct cell division or functional specialization. Previous studies established that homologs of the oxysterol-binding protein (OSBP) in S. cerevisiae, which comprise the Osh protein family, are necessary for efficient polarized exocytosis by supporting a late post-Golgi step. We define this step as the docking of a specific sub-population of exocytic vesicles with the plasma membrane. In the absence of other Osh proteins, yeast Osh4p can support this process in a manner dependent upon two lipid ligands, PI4P and sterol. Osh6p, which binds PI4P and phosphatidylserine, is also sufficient to support polarized exocytosis, again in a lipid-dependent manner. These data suggest that Osh-mediated exocytosis depends upon lipid binding and exchange without a strict requirement for sterol. We propose a two-step mechanism for Osh protein-mediated regulation of polarized exocytosis by using Osh4p as a model. We describe a specific in vivo role for lipid binding by an OSBP-related protein (ORP) in the process of polarized exocytosis, guiding our understanding of where and how OSBP and ORPs may function in more complex organisms.

  PublisherDOI

• Biosecurity in the age of Big Data: a conversation with the FBI

  Molecular Biology of the Cell · 2015-11-05 · 13 citations

  articleOpen access1st authorCorresponding

  New scientific frontiers and emerging technologies within the life sciences pose many global challenges to society. Big Data is a premier example, especially with respect to individual, national, and international security. Here a Special Agent of the Federal Bureau of Investigation discusses the security implications of Big Data and the need for security in the life sciences.

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• Secretory Vesicles Deliver Cdc42p to Sites of Polarized Growth in S. cerevisiae

  PLoS ONE · 2014-06-19 · 8 citations

  articleOpen accessSenior authorCorresponding

  The activation and localization of the Rho-family GTPase Cdc42p at one pole of a cell is necessary for maintaining an axis of polarized growth in many animal and fungal cells. How the asymmetric distribution of this key regulator of polarized morphogenesis is maintained is not fully understood, though divergent models have emerged from a congruence of multiple studies, including one that posits a role for polarized secretion. Here we show with S. cerevisiae that Cdc42p associates with secretory vesicles in vivo.

  PublisherOA PDFDOI

• Cell cycle checkpoint regulators reach a zillion

  Cell Cycle · 2013-05-15 · 55 citations

  reviewOpen accessSenior authorCorresponding

  Entry into mitosis is regulated by a checkpoint at the boundary between the G2 and M phases of the cell cycle (G2/M). In many organisms, this checkpoint surveys DNA damage and cell size and is controlled by both the activation of mitotic cyclin-dependent kinases (Cdks) and the inhibition of an opposing phosphatase, protein phosphatase 2A (PP2A). Misregulation of mitotic entry can often lead to oncogenesis or cell death. Recent research has focused on discovering the signaling pathways that feed into the core checkpoint control mechanisms dependent on Cdk and PP2A. Herein, we review the conserved mechanisms of the G2/M transition, including recently discovered upstream signaling pathways that link cell growth and DNA replication to cell cycle progression. Critical consideration of the human, frog and yeast models of mitotic entry frame unresolved and emerging questions in this field, providing a prediction of signaling molecules and pathways yet to be discovered.

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• A Detour for Yeast Oxysterol Binding Proteins

  Journal of Biological Chemistry · 2012-02-15 · 69 citations

  reviewOpen access

  Oxysterol binding protein-related proteins, including the yeast proteins encoded by the OSH gene family (OSH1-OSH7), are implicated in the non-vesicular transfer of sterols between intracellular membranes and the plasma membrane. In light of recent studies, we revisited the proposal that Osh proteins are sterol transfer proteins and present new models consistent with known Osh protein functions. These models focus on the role of Osh proteins as sterol-dependent regulators of phosphoinositide and sphingolipid pathways. In contrast to their posited role as non-vesicular sterol transfer proteins, we propose that Osh proteins coordinate lipid signaling and membrane reorganization with the assembly of tethering complexes to promote molecular exchanges at membrane contact sites.

  PublisherOA PDFDOI

• Intraflagellar transport—the “new motility” 20 years later

  Molecular Biology of the Cell · 2012-02-29 · 19 citations

  article1st authorCorresponding

  Intraflagellar transport is the rapid, bidirectional movement of protein complexes along the length of most eukaryotic cilia and flagella. Discovery of this intracellular process in Chlamydomonas reinhardtii 20 years ago led to a rapid discovery of cellular mechanisms that underlie a large number of human ciliopathies. Described herein are the events that led to this discovery.

  PublisherDOI

Recent grants

• Oxysterol Binding Proteins in Polarized Morphogenesis : Intersection of Vesicular & Non-vesicular Traffic

  NSF · $532k · 2007–2012

• INNER CENTROMERE TARGETING OF THE CHROMOSOME PASSENGER COMPLEX

  NIH · $10.6M · 2011–2016

Frequent coauthors

• Shubha Dighe

  University of Virginia

  10 shared

• Stanley Fields

  University of Washington

  6 shared

• Hay-Oak Park

  The Ohio State University

  5 shared

• Kimberly Yasutis

  University of Virginia

  5 shared

• Joel L. Rosenbaum

  The Ohio State University

  4 shared

• Christopher Beh

  Simon Fraser University

  4 shared

• David G. Drubin

  University of California, Berkeley

  4 shared

• Erfei Bi

  University of Pennsylvania

  3 shared