The rupee erased its marginal gains today and was trading 6 paise down against the US dollar, to 53 rupees 11 paise on rising demand for the American currency from banks as it strengthened in the global market.Earlier,the rupee resumed lower at 53 rupees 9 paise a dollar as against the last closing level of 53.05. Later, it gained marginally and moved between 53 and 53.16 per dollar before quoting at 53.11 in late morning trade.