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LytM factor Alr3353 affects filament morphology and cell–cell communication in the multicellular cyanobacterium Anabaena sp. PCC 7120
Author(s) -
Bornikoel Jan,
Staiger Julia,
Madlung Johannes,
Forchhammer Karl,
Maldener Iris
Publication year - 2018
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13929
Subject(s) - heterocyst , biology , peptidoglycan , microbiology and biotechnology , protein filament , multicellular organism , cell wall , anabaena , cell , lysis , biophysics , mutant , biochemistry , cyanobacteria , genetics , bacteria , gene
Summary Heterocyst‐forming cyanobacteria are organized as multicellular filaments of tightly interacting, functionally specialized cells. N 2 ‐fixing heterocysts differentiate from vegetative cells under nitrogen limitation in a semi‐regular pattern along the filament. Diazotrophic growth requires metabolite exchange between neighboring cells within the filament. This exchange occurs via cell–cell junction complexes that span the gap between the plasma membranes and thereby cross the septal peptidoglycan through an array of uniform nanopores formed by AmiC‐type cell wall hydrolases. We investigated how the lytic hydrolase AmiC1 (Alr0092) from Anabaena sp. PCC 7120, whose activity needs to be tightly controlled to avoid cell lysis, is regulated by the LytM factor Alr3353. Inactivation of alr3353 resulted in significantly fewer nanopores and as a consequence, a lower rate of fluorescent tracer exchange between cells. The mutant was not able to grow with N 2 as sole nitrogen source, although heterocysts were formed. Alr3353 localized mainly to fully developed intercellular septa of vegetative cells. The purified protein bound to peptidoglycan and enhanced the hydrolytic activity of AmiC1 in vitro . Our data show that the LytM factor Alr3353 regulates nanopore formation and cell–cell communication by directly interacting with AmiC1.