Subl/PC4, the well-known general transcription cofactor, has multiple functions in transcription and DNA repair.Here we present the crystal structure at 2.7(A) resolution of MoSub1, the Sub1/PC4 orthologue from the rice blast fungus, Magnaporthe oryzae, bound to a (dT19G) oligonucleotide.The structure of the MoSub1-DNA complex superimposes well on to the DNA free structure with an overall RMSD of 1.0(A) and several key residues undergo small shifts towards the DNA to facilitate binding.Comparing to PC4, the network of interactions between MoSub1 and DNA is significantly altered although it binds DNA using the same conserved DNA binding motif.Moreover, the interaction site of MoSub1 with the ssDNA is smaller than that of PC4, at four nucleotides (nt) per monomer rather than the five bound by each PC4 monomer.The nature of the MoSub1/PC4 DNA-protein interface was also probed by mutation of W89 of PC4, a key residue close to the site of DNA conformational change and equivalent to Y74 in MoSub1.The conservative mutation of W74Y does not diminish the DNA binding affinity with the dT4 or dT5.It is still unknown that which one could has a key role in DNA recognition by MoSub1 contributing to both overall binding site size as well as making specific interactions with in the protein-nucleic acid interface.