Noun + Onomatopoeia + する

We use onomatopoeia so little in English, but they're painfully prevalent in everyday Japanese language. I say painfully because they're extremely difficult to memorize, seeing as many of them have nothing that would clue you in to the meaning, other than obvious ones like どきどき.

Anyway, a noun が + onomatopoeia + する can be used to describe your physical/psychological state, or the way something looks or feels. It basically translates to "is" with the onomatopoeia being an equivalent adjective or verb in English.

机がガタガタして、書きにくい。
The desk is rickety, so it's difficult to write.

アヤト見ると、心がドキドキする。
Whenever I see Ayato, my heart races.

歯がシクシクする。歯医者に行かなきゃなんないけど、いやだなあ。
My tooth is throbbing. I've gotta go to the dentist, but it suuucks.

シュウの目がキラキラして、きれいだね。
Shuu's eyes are glittering, they're so beautiful.