Analysis Of ORFs And Their Functions In The Gaps In The DNA Fragment Of The Gum Gene Cluster From Xanthomonas Campestrispv. Campestris 8004

The transcription of the gum operon in the Xanthomonas campestris pv. campestris 8004(Xcc 8004) and its TnSgusAS transposon insertion mutants of the gum genes was comparatively analyzed by the RT-PCR. These results showed that TnSgusAS insertion has the strong complete polarity. This result also verified that these three gum genes (gumK,gummL,gumM)form the second transcription in the gum gene operon.The insertion sites of Tn5gusA5 in four mutants(TGL243,TGL14,TGL233 and TGL40) were located by methods of TAIL-PCR and sequencing. Biological and rheological characters were deterinated and analysised. The results showed the production of pigment in TGL243 were much lower than that in Xrc8004.lt is about 34% of Xcc8004; Production of pigment in TGL40 were much higher than that in Xcc8004.It is about 130% of Xcc8004; The ingredient and viscosity of excellular poysacchride (EPS) were changed in TGL233.The production of viscosity in TGL233 were 63% of Xcc8004.The transcription of gap between gumA and gumB has been analysised and two transcriptional units(ORF243 and ORF233) has been found .For further study, we constructed tow intergrated mutants of ORF243 and ORF233 successfully, named TGL243# and TGL233#. The pigment production of TGL243# like TGL243 were much lower than that of Xcc8004. The viscosity production of TGL233# were 63%.By the searching of ncbi blast, the results revealed that the deduced product encoded by ORF243 are predicated transcriptional regulators. So, we conclude ORF243 may be relevant to pigment production, ORF243 may be relevant to viscosity production and ingredient of EPS.