Crystallographic analysis of an RNA polymerase σ-subunit fragment complexed with −10 promoter element ssDNA: quadruplex formation as a possible tool for engineering crystal contacts in protein–ssDNA complexes

Crystallographic analysis of an RNA polymerase σ-subunit fragment complexed with −10 promoter element ssDNA: quadruplex formation as a possible tool for engineering crystal contacts in protein–ssDNA complexes