[BioC] Motif search

[nooshin]

Dear mailing list,

I'm so new in doing sequence analysis and I have a small project to do, 
which I need help for.
I have a known motif of binding site for one TF in Arabidopsis thaliana 
and I have to find out if this motif is enriched in 500-bps sequences 
from a set of genes. I don't know any package or function for this. I 
would be so thankful if anybody could help me.

Thanks,
Nooshin