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Oligomerization and higher‐order assembly contribute to sub‐cellular localization of a bacterial scaffold
Author(s) -
Bowman Grant R.,
Perez Adam M.,
Ptacin Jerod L.,
Ighodaro Eseosa,
FoltaStogniew Ewa,
Comolli Luis R.,
Shapiro Lucy
Publication year - 2013
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.12398
Subject(s) - caulobacter crescentus , biology , trimer , mutant , amino acid , microbiology and biotechnology , scaffold protein , protein subcellular localization prediction , linker , subcellular localization , protein domain , protein structure , cell division , biochemistry , cell , dimer , signal transduction , chemistry , gene , cell cycle , organic chemistry , cytoplasm , computer science , operating system
Summary In C aulobacter crescentus , the PopZ polar scaffold protein supports asymmetric cell division by recruiting distinct sets of binding partners to opposite cell poles. To understand how polar organizing centres are established by PopZ , we investigated a set of mutated PopZ proteins for defects in sub‐cellular localization and recruitment activity. We identified a domain within the C ‐terminal 76 amino acids that is necessary and sufficient for accumulation as a single subcellular focus, a domain within the N ‐terminal 23 amino acids that is necessary for bipolar targeting, and a linker domain between these localization determinants that tolerates large variation. Mutations that inhibited dynamic PopZ localization inhibited the recruitment of other factors to cell poles. Mutations in the C ‐terminal domain also blocked discrete steps in the assembly of higher‐order structures. Biophysical analysis of purified wild type and assembly defective mutant proteins indicates that PopZ self‐associates into an elongated trimer, which readily forms a dimer of trimers through lateral contact. The final six amino acids of PopZ are necessary for connecting the hexamers into filaments, and these structures are important for sub‐cellular localization. Thus, PopZ undergoes multiple orders of self‐assembly, and the formation of an interconnected superstructure is a key feature of polar organization in C aulobacter .