Analysis of <i>dofA</i> , a <i>fruA</i> -Dependent Developmental Gene, and Its Homologue, <i>dofB</i> , in <i>Myxococcus xanthus</i>

<jats:title>ABSTRACT</jats:title> <jats:p> The developmentally regulated gene <jats:italic>dofA</jats:italic> , identified from pulse-labeling experiments by two-dimensional gel electrophoresis, and its homologue, <jats:italic>dofB</jats:italic> , were cloned and characterized in <jats:italic>Myxococcus xanthus</jats:italic> . Deletion of <jats:italic>dofA</jats:italic> and <jats:italic>dofB</jats:italic> did not affect the vegetative growth and development of <jats:italic>M. xanthus. dofA</jats:italic> was specifically expressed during development, while <jats:italic>dofB</jats:italic> expression was observed during vegetative growth and development. The <jats:italic>dofA-lacZ</jats:italic> fusion was introduced into a <jats:italic>fruA</jats:italic> mutant and A, B, C, D, and E extracellular signal mutants. The pattern of <jats:italic>dofA</jats:italic> expression in the C signal mutant was similar to that of the wild-type strain, while <jats:italic>dofA</jats:italic> expression was not detected in the <jats:italic>fruA</jats:italic> mutant. These results are consistent with those of the pulse-labeling experiments. <jats:italic>dofA</jats:italic> expression was reduced in A and E signal mutants, whereas <jats:italic>dofA</jats:italic> expression was delayed in B and D signal mutants. The patterns of expression of the <jats:italic>dofA</jats:italic> gene in the <jats:italic>fruA</jats:italic> mutant and the five signal mutants are strikingly similar to that of the <jats:italic>tps</jats:italic> gene, which encodes protein S, a major component of the outer surface of the myxospore; this result suggests that the <jats:italic>dofA</jats:italic> and <jats:italic>tps</jats:italic> genes are similarly regulated. The involvement of a highly GC-rich inverted repeat sequence (underlined), <jats:underline>CGGCCCCCGA</jats:underline> TTCG <jats:underline>TCGGGGGCCG</jats:underline> , in developmentally regulated <jats:italic>dofA</jats:italic> expression is suggested. </jats:p>