MOLECULAR CHARACTERIZATION OF A MUTATION THAT DISRUPTS AGGLUTINATION
IN CHLAMYDOMONAS
AM Campbell, AJ Coble, TH Ch'ng, LD Cohen, EM Long*, KM Russo, and EV
Armbrust**
Biology Department, Davidson College, Davidson, NC, and *Molecular and
Cellular Biology Program and **Marine Molecular Biotechnology Laboratory,
School of Oceanography, University of Washington, Seattle, WA
Presented at the American Society for Cell Biology Annual meeting in
1998, San Francisco, CA.
Abstract
When Chlamydomonas reinhardtii gametes of opposite mating type
are mixed, they rapidly recognize and interact with one another via flagella
localized agglutinins. To learn more about this recognition system, insertional
mutagenesis was used to generate a mating type minus strain that is unable
to agglutinate with mating type plus gametes. RNA blot analysis indicates
that the mutant strain lacks a mRNA of about 4.4 kb that is normally expressed
in vegetative cells and wild-type gametes of both mating types. We have
sequenced the wild-type version of the disrupted gene and it displays strong
homology to a class of H+-ATPases localized to the plasma membrane. We now
refer to this ATPase as Pmh1 (for plasma membrane H+-ATPase). Vegetative
cells display no obvious defects; only agglutination of gametes seems to
have been affected. One hypothesis is that an internal compartment in pmh1
cells has the wrong pH which results in inadequate posttranslational modification
of agglutinin. Chloroquine and Folimycin (an H+-ATPase inhibitor) produced
pleiotrophic phenotypes including failure to agglutinate. Additional experiments
are underway to test the extent of glycosylation in pmh1 cells.
Generation of Mutant Strain
Phenotype
RNA Analysis
Chlamy Sequence
Alignment
Constructs
Model
Summary
© Copyright 2000 Department of Biology, Davidson
College, Davidson, NC 28036
Send comments, questions, and suggestions to: macampbell@davidson.edu