Pseudomonas syringae pv. phaseolicola에 의한 에틸렌 생합성

Abstract

The purport of this paper is to study the effects of various substrates on biosynthesis of ethylene in the intact cell and the cell-free system by the Kudzu strain of Pseudomonas syringae pv. phaseolicola causing halo blight. In the intact cell of P. syringae, optimal codition for ethylene production was achieved at pH 7.5 and 30℃. Ethylene was most effectively produced from amino acids such as Asn, Gln, Asp and Glu. In this case, ethylene production efficiency followed the above-written order of the items. While ethylene production from α-KG was gradually increased throughout 51h incubation period Although sugars such as saccharose, fructose were also good substrates, ethylene production was smaller than that with Asn. Ethylene production induced by citrate, α-KG and OAA was further enhanced by histidine and arginine. The same was true with amino acids. On the otherhand, the cell-free ethylene-forming system was used as a tool for the elucidation of the biochemical reaction involved in the formation of ethylene by P. syringae. Ethylene was most effectively produced from α-KG at 0.5mM but was decreased in production at 5mM. Amount of ethylene produced from Glu at 10mM was increased 60% more than at 0.5mM and citrate, Gln, OAA and Ser were also better substrates than sugars. Ethylene production in the cell-free system required the presence of α-KG and ferrous ion and was markedly stimulated by DTT and histidine. The results obtained in this work suggest that α-KG may be a more direct precursor of bacterial ethylene production than any other substrates tested.;식물의 고조병균인 Pseudomonas syringae pv. phaseolicola의 intact cell과 cell-free system에 의한 ethylene생성에서 다양한 기질의 영향을 조사하였다. Intact cell에서 ethylene생성을 극대화 하기위한 전환조건은 30℃, pH7.5로 조사되었고, 각종 유기산 및 아미노산, 당류의 다양한 기질의 전환효과를 검토한 결과, 당류보다는 아미노산과 유기산이 Asn>Gln>Asp>Glu>α-KG>citrate＞OAA순으로 많은양의 ethylene을 생성하였다. 또한 ethylene생성에 대한 유기산과 아미노산의 상승효과를 검토하여 arginine과 histidine이 현저한 효과가 있음을 확인하였다. P. syringae의 cell-free extract에 의한 ethylene생성은, ethylene생성의 생화학적 반응을 설명해 줄 수 있는 cell-fee system의 조제가 매우 주요하여, 이 system을 사용한 다양한 기질의 전환효과를 검토하였다. 그 결과 α-KG를 기질로 했을때, 0.5mM에서 310.8(nl·mg protein^(-1)·h^(-1))로 가장 많은 ethylene을 생성한 반면 5mM에서는 감소하였고, 아미노산중 Glu도 10mM에서 많은 ethylene을 생성하였다. 또한 당류보다는 citrate와 Gln, OAA, Ser이 효과적이었다. Cell-free system에서 ethylene생성에 대한 반응액내 각 성분효과를 조사한 결과, 효과적인 기절로서 α-KG와 ferrous ion이 필요하며, DTT와 histidine에 의해 크게 증가되는것으로 관찰되었다. 식물에서의 ethylene전구물질인 methionine은intactcell과cell-free system의 ethylene생성에 효과가 없었고, AVG에 의해 저해되지 않았기 때문에 식물과는 다른 경로로 추정된다. P syringae의 cell-free system에 transaminase 억제제인 AOA를 사용한결과, α-KG로부터 ethylene생성은 억제하지 않았으나, Glu에 의한 ethylene생성은 0.2mM AOA에 의해 약 95%이상 크게 억제되어, Glu에 의한 ethylene생성은 transaminase에 의해 α-KG로 된후 ethylene으로 전환될 것이라 생각되며, 앞으로 두 화합물에 대한 연구가 행해져야 할 것이다.