* Nikkei falls to lowest since April 2
* Topix's 33 subsectors all in the red
* Exporters lose ground after yen rises to 6-week high vs dollar
By Ayai Tomisawa
TOKYO, May 8 (Reuters) - Japan's Nikkei tumbled 1.5 percent to a five-week low on Wednesday as fears there might be a breakdown in U.S.-China trade negotiations continued to weigh on the market, while a stronger yen pulled down exporters.
Investors were spooked by a sell-off in Wall Street overnight, as the Dow Jones Industrial Average suffered its second-biggest daily percentage drop of the year.
The Nikkei share average shed 321.13 points to end at 21,602.59, the lowest closing level since April 2, following a 1.5 percent drop on Tuesday, when investors returned to the market after a 10-day break for Japan's Golden Week holidays and celebrations to mark the ascent of a new emperor to the throne.
"The market before the Golden Week was optimistic. Investors had expected that the U.S.-China trade talks would be resolved soon but things are looking serious," said Hiroyuki Ueno, a senior strategist at Sumitomo Mitsui Trust Asset Management.
Investors are now focused on trade talks on Thursday and Friday in Washington, where Chinese Vice Premier Liu will try to salvage a deal that would avoid a sharp increase in tariffs on Chinese goods ordered by U.S. President Donald Trump.
Trump said on Sunday that he would raise tariffs on $200 billion worth of Chinese goods to 25 percent from 10 percent, while U.S. trade negotiators said late on Monday that China had backtracked from commitments made earlier.
The prospect of a prolonged tariff war kept China-related stocks sliding. Construction equipment makers Komatsu Ltd plunged 2.9 percent, and Hitachi Construction Machinery dropped 2.7 percent.
Exporters lost ground after the dollar slipped 0.3 percent to 109.92 yen and briefly touched a six-week low of 109.905 yen.
Honda Motor fell 2.8 percent, Hino Motors declined 2.6 percent, TDK Corp dropped 2.6 percent and Hitachi Ltd plunged 3.2 percent.
Yamaha Motor tumbled 13 percent after its January-March operating profit dropped 12.8 percent from a year earlier.
The broader Topix dropped 1.7 percent to 1,572.33, with all 33 subsectors were in the red.
Declining issues outnumbered advancing ones 1,804 to 287. (Editing by Simon Cameron-Moore)