Probably required for N-acetylation of some chloroplast precursor proteins and efficient accumulation of thylakoid multiprotein complexes. In yeast, can replace the NatC complex (composed of MAK3, MAK10 and MAK31) by acetylating N termini of endogenous proteins and the N-terminus Met of L-A virus Gag protein. However, the formation of a NatC complex is not required for this function. acetyl-CoA + N-terminal L-methionyl-L-leucyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-leucyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-isoleucyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-isoleucyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-phenylalanyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-phenylalanyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-tryptophyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-tryptophyl-[protein] acetyl-CoA + N-terminal L-methionyl-L-tyrosyl-[protein] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-L-tyrosyl-[protein] Expressed in roots, leaves, flowers and siliques. Reduced plant size and pale-green leaves due to decreased chlorophyll concentration. Belongs to the acetyltransferase family. MAK3 subfamily.