OmpA signal peptide leads to heterogenous secretion of B. subtilis chitosanase enzyme from E. coli expression system

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Table 1 Enzyme activity and secretion efficiency

	Induction time (h)	Enzymatic activity (total units)^a		Fold change^b
	Induction time (h)	Native Sp	OmpA Sp	Fold change^b
Broth	0	85.5 ± 2.00	98.0 ± 2.92	1.15
	4	115 ± 1.5	244 ± 5.1	2.12
	20	265 ± 2.0	1386 ± 2.6	5.23
Periplasm	0	0.93 ± 0.02	0.99 ± 0.01	1.06
	4	2.03 ± 0.01	22.2 ± 0.20	10.9
	20	4.90 ± 0.09	27.6 ± 0.69	5.63
Cytosol	0	21.3 ± 0.02	20.5 ± 0.35	0.96
	4	388 ± 2.6	561 ± 12.8	1.45
	20	528 ± 5.1	564 ± 0	1.07
Total	0	108 ± 2.0	119 ± 3.3	1.10
	4	505 ± 1.2	828 ± 7.5	1.64
	20	798 ± 3.0	1978 ± 3.2	2.48
Secretion	0	79.3 ± 0.39	82.0 ± 0.21	1.03
Efficiency	4	22.7 ± 0.34	29.5 ± 0.88	1.30
(%)^c	20	33.2 ± 0.38	70.1 ± 0.01	2.11

Expression and secretion of B. subtilis Csn into different compartments of the E. coli host harboring Nat-Csn/pMY202 or OmpA-Csn/pMY202, which contain native (Native Sp) or OmpA (OmpA Sp) signal peptides
^aTotal enzyme activity from 50 mL culture. The experiments were done in duplicate and the average values with standard deviations are reported. The enzyme was induced for over expression with 0.5 mM IPTG
^bFold change indicates the relative values of the yields or secretion efficiencies of constructs with different signal peptides from different compartments (OmpA Sp divided by native Sp)
^cSecretion efficiency was calculated from the percentage of the enzyme activity from culture broth plus periplasmic space divided by the total enzyme activities from all three compartments