THE LEGIONELLA-MICDADEI FLAGELLIN - EXPRESSION IN ESCHERICHIA-COLI K-12 AND DNA-SEQUENCE OF THE GENE

To study the structure and function of the Legionella flagellum, we sc reened a genomic L. micdadei library in Escherichia coli for expressio n of the flagellin (Fla) subunit. One recombinant clone, JM105 (pHI558 8), producing a truncated Fla protein of 40.5 kDa was identified. The plasmid pHI5588 carried a L. micdadei DNA insert of 5 kb, containing c a 95% of the fla gene. The complete DNA sequence of the L. micdadei fl a gene was obtained by combining sequence data from pHI55588 with resu lts using a polymerase chain reaction-based system for genome walking (vectorette PCR). The L. micdadei fla gene shared a high degree of hom ology with other flagellin genes in the amino- and carboxy termini, wh ereas the central region was found to be nonconserved. The fla sequenc e will facilitate the cloning of Fla proteins from other Legionella sp ecies and the study of flagella in the pathogenesis of Legionnaires' d isease.