High-throughput identification of protein localization dependency networks

Proc Natl Acad Sci U S A. 2010 Mar 9;107(10):4681-6. doi: 10.1073/pnas.1000846107. Epub 2010 Feb 22.

Abstract

Bacterial cells are highly organized with many protein complexes and DNA loci dynamically positioned to distinct subcellular sites over the course of a cell cycle. Such dynamic protein localization is essential for polar organelle development, establishment of asymmetry, and chromosome replication during the Caulobacter crescentus cell cycle. We used a fluorescence microscopy screen optimized for high-throughput to find strains with anomalous temporal or spatial protein localization patterns in transposon-generated mutant libraries. Automated image acquisition and analysis allowed us to identify genes that affect the localization of two polar cell cycle histidine kinases, PleC and DivJ, and the pole-specific pili protein CpaE, each tagged with a different fluorescent marker in a single strain. Four metrics characterizing the observed localization patterns of each of the three labeled proteins were extracted for hundreds of cell images from each of 854 mapped mutant strains. Using cluster analysis of the resulting set of 12-element vectors for each of these strains, we identified 52 strains with mutations that affected the localization pattern of the three tagged proteins. This information, combined with quantitative localization data from epitasis experiments, also identified all previously known proteins affecting such localization. These studies provide insights into factors affecting the PleC/DivJ localization network and into regulatory links between the localization of the pili assembly protein CpaE and the kinase localization pathway. Our high-throughput screening methodology can be adapted readily to any sequenced bacterial species, opening the potential for databases of localization regulatory networks across species, and investigation of localization network phylogenies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / classification
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Caulobacter crescentus / cytology
  • Caulobacter crescentus / genetics
  • Caulobacter crescentus / metabolism*
  • Cell Division
  • Cluster Analysis
  • DNA Transposable Elements / genetics
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microscopy, Fluorescence / methods
  • Models, Biological
  • Mutagenesis, Insertional
  • Mutation
  • Protein Array Analysis / instrumentation
  • Protein Array Analysis / methods*
  • Protein Interaction Mapping / instrumentation
  • Protein Interaction Mapping / methods*

Substances

  • Bacterial Proteins
  • DNA Transposable Elements
  • Luminescent Proteins