New function for Escherichia coli xanthosine phophorylase (xapA): genetic and biochemical evidences on its participation in NAD + salvage from nicotinamide

Table 2 Generation time (minutes) of Escherichia coli strains in different culture media*

No.	Strain	Pathway Deficiency	Medium M9		M9 + NA		M9 + NAD⁺		M9 + NAM
No.	Strain	Pathway Deficiency	Expected	Observed	Expected	Observed	Expected	Observed	Expected	Observed
1	BW25113	None	+	65.8	+	49.8	+	50.5	+	49.4
2	ΔnadC	dn	–	–	+	49.4	+	49.4	+	53.4
3	ΔnadC ΔpncA	dn, I	–	–	+	50.3	+	49.2	–	380.8
4	ΔnadC ΔpncA ΔxapA	dn, I	–	–	+	49.2	+	50.0	–	620.4
5	ΔnadC ΔpncA ΔxapA/pBAD-xapA	dn, I	–	NT	+	NT	+	+	–	376.4
6	ΔnadC ΔpncA ΔxapA/pBAD-EGFP	dn, I	–	NT	+	NT	+	+	–	626.8
7	ΔnadC ΔpncA ΔnadR	dn, I, III	–	–	+	51.1	+	NT	–	–
8	ΔnadC ΔpncA ΔxapA ΔnadR	dn, I, III	–	–	+	49.7	+	NT	–	–

*Notes: NA, nicotinic acid; NAM, nicotinamide; NAD⁺, nicotinamide adenine dinucleotide; NT, not tested; –, No proliferation; +, proliferation; dn, de novo NAD⁺ synthesis; I, NAD⁺ salvage pathway I; III, NAD⁺ salvage pathway III.

ISSN: 1471-2180