UPDATE 3-SumTotal to be bought by Vista Equity for $160 mln

* Agrees to be bought by Vista Equity for $160 mln

* Says Vista Equity to pay $4.85/share in cash

* Says paid Accel-KKR termination fee of $6.67 mln

* Discovery Group says will back Vista deal

* SumTotal shares down as much as 3 percent

(Adds analyst comments, shareholder comments, updates share movement)

By Deepti Govind

BANGALORE, May 27 (Reuters) - Software-maker SumTotal Systems Inc (SUMT.O: Quote, Profile, Research) agreed to be bought by its largest shareholder, Vista Equity Partners, for $160 million and terminated its previous deal with Accel-KKR, ending a long-drawn bidding war between the two private equity firms.

The revised offer price of $4.85 is at a slight discount to Tuesday's closing price of SumTotal shares, but represents a premium of 141 percent over its closing price on April 3, the last trading day before Vista's initial proposal for the company.