• Journal of Microbiology and Biotechnology
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• 제9권5호
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• pp.637-645
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• 1999

Two putative regulator genes, mocR and mocS, of the moc (mannityl opine catabolism) operons in pTi15955 of the octopine-/mannityl opine-type Agrobacterium tumefaciens strain 15955, were tested for their possible roles as repressors in the moc operons. The regions upstream of macC and mocD, the first structural genes in the two divergently oriented moc operons, were transcriptionally fused into the promoterless lacZ reporter gene. Each of the lacZ-fusions was introduced into Agrobacterium strain UIA5, a Ti plasmid-cured derivative, harboring either a mocR or a mocS clone. The resulting strains were grown in media containing various sugar sources, and the $\beta$-galactosidase activities were quantitatively measured. The results suggested that MocR repressed the expression of macC and macD. The expression of the fused $\beta$-galactosidase was not induced by mannopine (MOP) or possible catabolic intermediates of the opine, e.g. santhopine (SOP), glucose, mannose, or glutamine. However, the repression was significantly relieved by the supplementation of MOP and the concomitant introduction of the agcA gene encoding MOP cyclase that catalyzes the lactonization of MOP to agropine (AGR). These results suggested that AGR, rather than MOP or the other catabolic intermediates, is the inducer for the expression of the operon. On the contrary to previous report showing that the induction levels of macC and macD were lowered by the supplementation of inorganic nitrogen in media, the expression of these genes was not affected by the level of nitrogen in our reporter system. MocS did not strongly repress the expressions of macC and mocD. It is possible that MocS may be involved in the regulation of the operons present downstream of the moc operon, which are responsible for the utilization of mannopinic acid and agropinic acid.

• KSBB Journal
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• 제4권3호
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• pp.246-253
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• 1989

Agorobacterium rhizogenes에 의하여 유도된 당근(Daucus carota L. )의 hairy root를 배양하였으며 opine 유무에 대한 형질전환 확인 및 배지조성을 달리하여 성장률에 따른 색소함량을 비교하였고, 재분화된 식물체의 형태적 차이를 관찰하여 몇가지 결론을 얻었다. Hairy root는 균 접종 2-4주 후에 형성층 부위를 중심으로 유도되었다. 유도된 hairy root의 초기 배양에는 R.C.M 배지가 적합하였으며 MSO(2, 4-D $10^{-4} ml/ l, pH6, sucrose 5%, 질소원 0.03M 등)에서 최대 성장을 보여주었고 성장의 증가에 따른 색소의 형성은 비교적 안정하였다. 재분화된 식물체는 정상 식물체에 비하여 형태적으로 차이를 나타내었으며 형질전환된 hairy root 및 재분화된 식물체에서 mannopine 분석으로 Ri-plasmid에 의한 형질전환이 이루어졌음을 확인하였다.