TOKYO — Toyota’s dreaded moment is finally here: The Japanese automaker is set to shutter a major factory for the first time in its 73-year history, pulling the plug on a joint venture with General Motors and marking a new era of more aggressive cuts at the Japanese automaker.

Toyota will soon enter discussions to dissolve New United Motor Manufacturing, a 50-50 venture based in Fremont, California, that employs about 4,550 people, said Toyota spokesman Paul Nolasco.

GM quit the venture, dubbed Nummi, as part of its reorganization under bankruptcy protection last month. A final decision on closing the plant is expected in August, after talks between Toyota and the entity charged with liquidating GM assets, the Motors Liquidation Company or MLC.

“We have decided to discuss with the MLC what we would need to do to withdraw from our joint venture,” Mr. Nolasco said in Tokyo. “We’ve never shut down and ended a plant,” he said. “But we are in a really tough situation.”