Table 2.

Summary of the structure-function information available for the VIM-1 variants.

Variant	Closest variant for reference	Mutation(s) of interest	Localization	Comments a
VIM-2	VIM-1	H224Y	ASL10	Increased affinity for ceftazidime (KM value of 98 vs. 794 μM), compared to VIM-1 [40, 108].
VIM-31	VIM-2	Y224H	ASL10	Overall decreased activity (e.g. ampicillin: 0.9 vs. 1.4 μM−1 s−1; ceftazidime: 0.005 vs. 0.05 μM−1 s−1; meropenem: 0.3 vs. 2.5 μM−1 s−1), compared to VIM-2 [113].
VIM-4 VIM-13 VIM-19 VIM-23	VIM-1	S228R	ASL10	Decreased activity for extended-spectrum cephalosporins, compared to VIM-1 (e.g. cefepime: 0.03 vs. 0.4 μM−1 s−1, for VIM-13 and VIM-1, respectively [117]).
VIM-11	VIM-2	N165S	Near ASL10	Increased activity for ceftazidime (0.13 vs. 0.03 μM−1 s−1); cefepime (0.083 vs. 0.03 μM−1 s−1); and cefpirome (0.6 vs. 0.28 μM−1 s−1), compared to VIM-2 [119].
		S60K F61L		Enlarged active-site cavity, likely due to increased flexibility of ASL3 and loss of H- bonding at ASL10. Overall decreased activity for most cephalosporins (e.g. cephalothin: 4 vs. 12 μM−1 s−1; ceftazidime: 0.012 vs. 0.05 μM−1 s−1; cefotaxime: 2.6 vs. 5.8 μM−1 s−1), compared to VIM-2 [171].
		D62G	ASL3
VIM-7	VIM-2	G63D
		A64T
		S68P
		Y224H	ASL10
		Y218P

^aBased on k_cat/K_M values, unless noted.