LPS is importance to Gram-negative bacteria, whose death results if it is mutated or removed.

1. 本句，使用importance 有误。应改为形容词important 或of importance。

2. whose death results if it is mutated or removed，是定语从句。whose 指代bacteria's ，表示“所属关系”。意为“细菌的死亡”。

3. result 用作动词，意为“发生；产生；出现”，相当于happen。

定语从句的翻译：

whose death results if it is mutated or removed.

如果发生突变或移除，革兰氏阴性菌就会死亡。