TABLE 1.

Activities of methenyl H₄MPT cyclohydrolase, NAD-dependent methylene H₄MPT dehydrogenase, and NADP-dependent methylene H₄MPT dehydrogenase in cell extracts of different methylotrophic bacteria

Organism	Major assimilation pathwaya	Grown on:	Activity (U/mg)b
			Methenyl H4MPT CH	Methylene H4MPT DH (NAD)	Methylene H4MPT DH (NADP)
α-Proteobacteria:
Methylobacterium extorquens AM1	Serine	Methanol	0.7	0.6	5.1
		Succinate	0.3	0.5	1.0
Methylobacterium organophilum XX	Serine	Methanol	0.3	0.1	1.3
		Succinate	0.1	0.1	0.2
Hyphomicrobium methylovorum GM2	Serine	Methanol	0.4	0.1	1.3
Methylosinus trichosporium OB3b	Serine	Methane	0.7	0.7	1.0
Xanthobacter autotrophicus	CBB	Methanol	0.6	0.1	0.2
		Nh + Methanol	0.3	0.03	0.2
Xanthobacter flavus H4-14	CBB	N + Methanol	0.2	0.2	0.4
Paracoccus denitrificansc	CBB	Methanol	<0.01	<0.01	<0.01
Rhodopseudomonas acidophilad,e	CBB	Succinate + Methanol	<0.01	<0.01	<0.01
Rhodobacter sphaeroides 2.4.1f	CBB	N	<0.01	<0.01	<0.01
β-Proteobacteria:
Methylobacillus flagellatum KT	RuMP	Methanol	1.0	1.1	1.8
Methylophilus methylotrophus AS1	RuMP	Methanol	0.6	0.2	0.4
γ-Proteobacteria:
Methylococcus capsulatus Bath	RuMP	Methane	0.7	0.5	1.7
Methylococcus thermophilus IIIp	RuMP	Methane	0.2	0.1	0.3
Methylomicrobium album BG8	RuMP	Methane	0.4	0.3	0.7
Methylomonas rubra 15sh	RuMP	Methane	0.6	0.4	0.6
Gram-positive bacteria:
Bacillus methanolicus MGA3	RuMP	Methanol	<0.01	<0.01	<0.01
Amycolatopsis methanolicag	RuMP	Methanol	<0.01	<0.01	<0.01
		Glucose	<0.01	<0.01	<0.01

^aCBB, Calvin-Benson-Bassham; RuMP, ribulose monophosphate. 

^bEnzyme activities were measured under standard assay conditions at room temperature. CH, cyclohydrolase; DH, dehydrogenase. 

^cContains a glutathione-linked formaldehyde dehydrogenase (32). 

^dContains a glutathione-linked formaldehyde dehydrogenase (36). 

^eCells were grown anaerobically in the light. 

^fContains a glutathione-linked formaldehyde dehydrogenase (2, 3). 

^gContains a mycothiol-linked formaldehyde dehydrogenase (27, 28). 

^hN, nutrient agar.