PageRank does not effect your ranking in the search engine rankings. PageRank, developed by Google recognizes the importance of a web page. Pages are scored from 0–10. The importance is determined by incoming links, with links from pages with a higher PageRank counting more.
So where PageRank can be important is where you getting links from. If they are coming from relevant (similar topic) web pages with a higher PageRank, that can help your rankings.