A nucleoprotein complex suitable for use in modifying a target nucleic acid sequence comprising a targeting nucleic acid and a modular polypeptide component, wherein said targeting nucleic acid comprises: (i) a targeting nucleic acid element complementary to a region of the target; (ii) a recognition element which specifically interacts with a nucleic acid recognition module of said modular polypeptide component and (iii) a connecting sequence which links said targeting element and said recognition element and said modular polypeptide component comprises as linked, separate functional modules: (a) said nucleic acid recognition module which is devoid of enzymic activity; (b) a DNA-binding domain for assisting in melting and/or unwinding of a double helix of the target, wherein the DBD recognises a predetermined sequence in the target, module (a) and said DBD not being naturally found in linkage, (c) an effector component for use in modifying the target whereby site-specific modification directed by said TE and DBD will occur, wherein said DBD is a polypeptide sequence of no more than 70-75 amino acid residues; wherein the length of the modular polypeptide component is no more than 300 amino acids in length; and wherein module (b) is joined to module (a) and module (c) respectively; optionally wherein modules (a), (b) and (c) are joined by a first and/or a second linker. wherein said targeting nucleic acid comprises: (i) a targeting nucleic acid element complementary to a region of the target; (ii) a recognition element which specifically interacts with a nucleic acid recognition module of said modular polypeptide component and (iii) a connecting sequence which links said targeting element and said recognition element (i) a targeting nucleic acid element complementary to a region of the target; (ii) a recognition element which specifically interacts with a nucleic acid recognition module of said modular polypeptide component and (iii) a connecting sequence which links said targeting element and said recognition element and said modular polypeptide component comprises as linked, separate functional modules: (a) said nucleic acid recognition module which is devoid of enzymic activity; (b) a DNA-binding domain for assisting in melting and/or unwinding of a double helix of the target, wherein the DBD recognises a predetermined sequence in the target, module (a) and said DBD not being naturally found in linkage, (c) an effector component for use in modifying the target whereby site-specific modification directed by said TE and DBD will occur, (a) said nucleic acid recognition module which is devoid of enzymic activity; (b) a DNA-binding domain for assisting in melting and/or unwinding of a double helix of the target, wherein the DBD recognises a predetermined sequence in the target, module (a) and said DBD not being naturally found in linkage, (c) an effector component for use in modifying the target whereby site-specific modification directed by said TE and DBD will occur, wherein said DBD is a polypeptide sequence of no more than 70-75 amino acid residues; wherein the length of the modular polypeptide component is no more than 300 amino acids in length; and wherein module (b) is joined to module (a) and module (c) respectively; optionally wherein modules (a), (b) and (c) are joined by a first and/or a second linker.