Methylation of rRNA as a host defense against rampant group II intron retrotransposition

Table 1 Bacterial strains and plasmids

Bacteria	Relevant characteristics; comments	Reference
L. lactis IL1403	plasmid free; recipient strain, strain for all RTP assays; sequenced genome is available (GenBank: NC_002662)	[22]
E. coli DH5α	F⁻ endAI recAl hsdRl7 (rK⁻ mK⁻) deoR supE44 thi⁻J gyrA96 relA	Gibco-BRL
Plasmids	Relevant characteristics; comments	Reference
pLNRK-RIG	L. lactis/E. coli shuttle vector contains nisin-inducible promoter, nisR nisK, Cam^R, RIG cassette, intron donor	[21]
pGh4:ISS1	pG + host replicon, thermosensitive (replicates at 28 °C but lost above 37 °C), Erm^R	[23]
pRS01	co-integrant of conjugative plasmid pRS01 and pTRK28, Erm^R	[24]
pLNRK-GFP	Derived from pLNRK-RIG with green fluorescent protein (GFP) replacing the entire intron and RIG cassette. Cam^R	This study
pMN1343	pMN1343 Spc^R, contains intron homing site	[25]
pGh5: P_nisA	pG + host replicon, Erm^R, backbone of pGh5 from [23], with ISS1 removed, P_nisA inserted. Used as empty vector control in the wild-type background in complementation assays.	[23] and this study
pGh5: P_nisA rlmH	pGh5:P_nisA with the rlmH gene inserted under control of the P_nisA promoter. Used for complementation assays.	[23] and this study
pLNRK-SA	pLNRK smEx::Ll.LtrB ΔORF (SA)-nLIC; expression construct for Ll.LtrB intron with streptavidin aptamer in domain IVb, Cam^R	[26]

ISSN: 1759-8753