ComCED signal loop precisely regulates nlmC expression in Streptococcus mutans

Annals of Microbiology

Table 3 Effect of mutant comX, comED and comC on nlmC expression

Strain^a	Treatment^b	PnlmAB (Miller Unit)^c	PnlmC (Miller Unit)^c
WT	− CSP	247.0 ± 6.0	988.8 ± 47.8
WT	+ CSP	2307.1 ± 84.1	3155.9 ± 99.3
ΔcomX	− CSP	174.8 ± 1.7	1063.4 ± 125.2
ΔcomX	+ CSP	2261.3 ± 34.3	3273.3 ± 156.1
ΔcomED	− CSP	48.5 ± 1	57.8 ± 10.5
ΔcomED	+ CSP	55.8 ± 5.2	40.8 ± 14.6
ΔcomC	− CSP	153.2 ± 8.6	19.3 ± 1.1
ΔcomC	+ CSP	2231.5 ± 116.3	22.0 ± 1.8

The beta-galactosidase activity was calculated according to the formula: Miller Units = [10,00 × A₄₂₀/reaction time (min)] × OD₆₇₅ and the absorbance of A₄₂₀ and OD₆₇₅ were ONPG color reaction of beta-Galactosidase and the cell density, respectively, defined in “Materials and methods”
^aBackground of S. mutans strains discribled in Table 1. WT, ΔcomX, ΔcomED, ΔcomC: wild-type and deletion mutants of comX, comED or comC gene
^b − CSP: not supplying exogenous CSP as control in medium, + CSP: supplying with 0.8 μg/mL CSP in medium
^cDifferent background strains harboring nlmAB promoter-lacZ (PnlmAB) or nlmC promoter-lacZ (PnlmC)

ISSN: 1869-2044