Cell wall formation. Adds enolpyruvyl to UDP-N-acetylglucosamine (By similarity). Target for the antibiotic fosfomycin. phosphoenolpyruvate + UDP-N-acetyl-alpha-D-glucosamine = phosphate + UDP-N-acetyl-3-O-(1-carboxyvinyl)-alpha-D-glucosamine Cell wall biogenesis; peptidoglycan biosynthesis. This strain of S.pneumoniae has no heteroresistance to fosfomycin unlike other strains of this bacterium in which MurA1 is required for heteroresistance along with other as yet unknown factor(s). Heteroresistance is the ability of a clonal population to grow one or several subpopulations at a frequency of 10(-7) to 10(-3) in the presence of a higher antibiotic concentration than that predicted to be effective by measurement of the minimum inhibitory concentration (MIC). Belongs to the EPSP synthase family. MurA subfamily.