Biomaterial Database

Expression of two Rhizobium meliloti flagellin genes and their contribution to the complex filament structure. 1991

E Pleier, and R Schmitt

Lehrstuhl für Genetik, Universität Regensburg, Federal Republic of Germany.

The complex flagellar filaments of Rhizobium meliloti are composed of two related (87% identical) flagellins that are encoded by closely linked, separately transcribed genes, flaA and flaB (E. Pleier and R. Schmitt, J. Bacteriol. 171:1467-1475, 1989). To elucidate the role of the subunits, A and B, in assembling the complex filament, the wild-type alleles were replaced with defective ones containing a 2,249-bp deletion (accompanied by substitution of a kanamycin resistance cartridge), which eliminates 74% of flaA (3' end) and 85% of flaB (5' end). The resulting nonmotile, filamentless mutant, RU11011, was tested for complementation with wild-type flaA, flaB, and flaA flaB genes provided on the multiple-copy vector pRK290. Whereas flaA alone did not restore motility and filament production, both flaB and flaA flaB restored 20 to 30% of wild-type motility. Apparent causes of this reduced motility were fewer flagella per cell and/or shortened filaments sometimes ending in unusually thin, fragile structures. Tests with enzyme-linked antiflagellin antibodies indicated that flaA is expressed at higher levels than flaB and that multiple copies of flaA lead to reduced flagellin export. We conclude that the proximal portion of the complex filament is assembled from B subunits (not produced sufficiently to form full-length flagella) and that the distal portion is made from A subunits. Multiple copies of the strong flaA promoter may offset transcriptional controls that regulate the synthesis of flagellar structures required for flagellin export.

UI	MeSH Term	Description	Entries
D009024	Morphogenesis	The development of anatomical structures to create the form of a single- or multi-cell organism. Morphogenesis provides form changes of a part, parts, or the whole organism.
D009068	Movement	The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.	Movements
D002633	Chemotaxis	The movement of cells or organisms toward or away from a substance in response to its concentration gradient.	Haptotaxis
D002872	Chromosome Deletion	Actual loss of portion of a chromosome.	Monosomy, Partial,Partial Monosomy,Deletion, Chromosome,Deletions, Chromosome,Monosomies, Partial,Partial Monosomies
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D005408	Flagellin	A protein with a molecular weight of 40,000 isolated from bacterial flagella. At appropriate pH and salt concentration, three flagellin monomers can spontaneously reaggregate to form structures which appear identical to intact flagella.
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D005816	Genetic Complementation Test	A test used to determine whether or not complementation (compensation in the form of dominance) will occur in a cell with a given mutant phenotype when another mutant genome, encoding the same mutant phenotype, is introduced into that cell.	Allelism Test,Cis Test,Cis-Trans Test,Complementation Test,Trans Test,Allelism Tests,Cis Tests,Cis Trans Test,Cis-Trans Tests,Complementation Test, Genetic,Complementation Tests,Complementation Tests, Genetic,Genetic Complementation Tests,Trans Tests
D012231	Rhizobium	A genus of gram-negative, aerobic, rod-shaped bacteria that activate PLANT ROOT NODULATION in leguminous plants. Members of this genus are nitrogen-fixing and common soil inhabitants.
D015964	Gene Expression Regulation, Bacterial	Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.	Bacterial Gene Expression Regulation,Regulation of Gene Expression, Bacterial,Regulation, Gene Expression, Bacterial