FIELD: biotechnology.
SUBSTANCE: invention relates to biotechnology. A cytosine permease consisting of an amino acid sequence represented by SEQ ID NO: 1 is proposed, in which isoleucine, which is an amino acid corresponding to position 401 in SEQ ID NO: 3, is replaced by threonine. A polynucleotide encoding said cytosine permease, an Escherichia coli microorganism that produces L-tryptophan and contains said cytosine permease or a polynucleotide encoding said cytosine permease, and a method for producing L-tryptophan are also proposed.
EFFECT: invention makes it possible to increase the yield of L-tryptophan.
5 cl, 1 tbl, 2 ex
