1. Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
2. California Institute for Quantitative Biosciences-Berkeley (QB3-Berkeley), University of California, Berkeley, Berkeley, California, USA
3. Graduate Group in Microbiology, University of California, Berkeley, Berkeley, California, USA
4. Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA