Sumitomo researchers shed new light on natural rubber biosynthesis

Tokyo – Sumitomo Rubber Industries (SRI) has invented a technique for evaluating enzymes using artificial ‘nanodisc’ membranes, which “shed further light on the mechanisms” behind the biosynthesis of natural rubber.

The development emerged from ongoing joint research with professor Yuzuru Tozawa of Saitama University, associate professor Seiji Takahashi of Tohoku University and associate professor Satoshi Yamashita of Kanazawa University, SRI said 14 April.

“While previous evaluation techniques used natural membranes, this new technique uses artificial membranes, thereby eliminating environmental impurities to allow for higher precision evaluations,” the company explained.

The “ground-breaking” technique, it claimed, could lead to the discovery of “new significant constituents of natural rubber [that] will surely lead to the improvement of rubber yields.”

SRI said it envisages many other potential advancements, not least opening the door to laboratory biosynthesis of natural rubber.

Three specific proteins are known to play a key role in the synthesis of the long polyisoprene chains found in Pará rubber trees: Hevea rubber transferase 1 (HRT1); “HRT1-REF bridging protein (HRBP); and rubber elongation factor (REF).

However, explained SRI, it was unclear under which conditions HRT1 – an enzyme believed to bind multiple molecules together – fulfilled its particular function.

In the past, HRT1 has been observed synthesising isoprene chains when placed on natural membranes, such as those formed by rubber particles or yeast.

However, impurities in the natural membranes inevitably contaminate the test environment, making it impossible to identify the other constituents necessary for isoprene chain synthesis, said SRI.

The research team, therefore, developed a new enzyme evaluation technique that uses artificial membranes (nanodiscs) that contain no natural materials.

“Thanks to this breakthrough, we have now discovered that HRT1 synthesizes isoprene chains when both HRT1 and HRBP are present on one of these artificial membranes,” SRI reported.

“This was the first time that HRT1 has been observed performing this function on an artificial membrane,” according to the company.

 The next step, it said, will be “to find the significant component (?α) that causes isoprene chains to lengthen, which would make it possible to artificially biosynthesize natural rubber in a lab.”