ABSTRACT
Many Archaea use rotation of helical flagellar filaments for swimming motility. We isolated and characterized the flagellar filaments of Haloarcula marismortui, an archaeal species previously considered to be nonmotile. Two Haloarcula marismortui phenotypes were discriminated--their filaments are composed predominantly of either FlaB or FlaA2 flagellin, and the corresponding genes are located on different replicons. FlaB and FlaA2 filaments differ in antigenicity and thermostability. FlaA2 filaments are distinctly thicker (20-22 nm) than FlaB filaments (16-18 nm). The observed filaments are nearly twice as thick as those of other characterized euryarchaeal filaments. The results suggest that the helicity of Haloarcula marismortui filaments is provided by a mechanism different from that in the related haloarchaeon Halobacterium salinarum, where 2 different flagellin molecules present in comparable quantities are required to form a helical filament.
Subject(s)
Archaeal Proteins/metabolism , Chlorides/metabolism , Flagella/metabolism , Flagellin/metabolism , Haloarcula marismortui/metabolism , Amino Acid Sequence , Archaeal Proteins/chemistry , Archaeal Proteins/genetics , Flagella/chemistry , Flagella/genetics , Flagellin/chemistry , Flagellin/genetics , Haloarcula marismortui/chemistry , Haloarcula marismortui/genetics , Molecular Sequence Data , Sequence AlignmentABSTRACT
We examine distribution of flagellins along multicomponent flagellar filaments (FF) and protofilaments (PF) of the haloalkaliphilic archaeon Natrialba magadii using immunogold electron microscopy. A high specific polyclonal antibody raised to one of the flagellin types bound homogeneously to the undissociated FF along the full length. At the same time both uniformly labelled and completely unlabelled PF, outwardly indistinguishable one from another, were observed.
Subject(s)
Flagella/immunology , Flagella/ultrastructure , Flagellin/metabolism , Halobacteriaceae/metabolism , Electrophoresis, Polyacrylamide Gel , Flagellin/immunology , Halobacteriaceae/immunology , Halobacteriaceae/ultrastructure , Microscopy, ImmunoelectronABSTRACT
We have determined the nucleotide sequence of a flagellin gene locus from the haloalkaliphilic archaeon Natrialba magadii, identified the gene products among proteins forming flagella, and demonstrated cotranscription of the genes. Based on the sequence analysis we suggest that different regions of the genes might have distinct evolutionary histories including possible genetic exchange with bacterial flagellin genes.
