@article{sela_rawsthorne_mills_2007, title={Characterization of the lactococcal group II intron target site in its native host}, volume={58}, ISSN={["1095-9890"]}, DOI={10.1016/j.plasmid.2007.02.003}, abstractNote={The Lactococcus lactis group II intron (Ll.ltrB) retrohomes into the ltrB gene at high efficiency. To date, the critical DNA bases recognized in vivo by the Ll.ltrB ribonucleoprotein (RNP) have been exclusively elucidated in Escherichia coli. However, recent evidence indicates host-dependant differences in Ll.ltrB mobility, raising the possibility of limitations of the current model for RNP-homing site recognition in the native L. lactis host. In this work, intron retargeting experiments in L. lactis have demonstrated that adherence to specific target site critical bases is not sufficient to predict success or failure of chromosomal invasion, as in E. coli. Accordingly, a quantitative real-time PCR (QPCR) assay was developed to test target site nucleotides previously demonstrated as critical for homing in E. coli, for relevance in its native host. This two-plasmid QPCR homing assay is highly sensitive and, unlike previous E. coli-based assays, resolves differential homing efficiencies in the absence of selection. As in E. coli, deviation from wild type at target site positions -23, -21, -20, -19, and +5 resulted in lower homing efficiencies in L. lactis. Furthermore, the same trends are observed when assaying select variants in Enterococcus faecalis. Our results suggest that these target site positions are critical in both E. coli and L. lactis.}, number={2}, journal={PLASMID}, author={Sela, David A. and Rawsthorne, Helen and Mills, David A.}, year={2007}, month={Sep}, pages={127–139} }
 @article{madsen_mills_djordjevic_israelsen_klaenhammer_2001, title={Analysis of the genetic switch and replication region of a P335-type bacteriophage with an obligate lytic lifestyle on Lactococcus lactis}, volume={67}, ISSN={["1098-5336"]}, DOI={10.1128/AEM.67.3.1128-1139.2001}, abstractNote={The DNA sequence of the replication module, part of the lysis module, and remnants of a lysogenic module from the lytic P335 species lactococcal bacteriophage phi31 was determined, and its regulatory elements were investigated. The identification of a characteristic genetic switch including two divergent promoters and two cognate repressor genes strongly indicates that phi31 was derived from a temperate bacteriophage. Regulation of the two early promoters was analyzed by primer extension and transcriptional promoter fusions to a lacLM reporter. The regulatory behavior of the promoter region differed significantly from the genetic responses of temperate Lactococcus lactis phages. The cro gene homologue regulates its own production and is an efficient repressor of cI gene expression. No detectable cI gene expression could be measured in the presence of cro. cI gene expression in the absence of cro exerted minor influences on the regulation of the two promoters within the genetic switch. Homology comparisons revealed a replication module which is most likely expressed from the promoter located upstream of the cro gene homologue. The replication module encoded genes with strong homology to helicases and primases found in several Streptococcus thermophilus phages. Downstream of the primase homologue, an AT-rich noncoding origin region was identified. The characteristics and location of this region and its ability to reduce the efficiency of plaquing of phi31 10(6)-fold when present at high copy number in trans provide evidence for identification of the phage origin of replication. Phage phi31 is an obligately lytic phage that was isolated from commercial dairy fermentation environments. Neither a phage attachment site nor an integrase gene, required to establish lysogeny, was identified, explaining its lytic lifestyle and suggesting its origin from a temperate phage ancestor. Several regions showing extensive DNA and protein homologies to different temperate phages of Lactococcus, Lactobacillus, and Streptococcus were also discovered, indicating the likely exchange of DNA cassettes through horizontal gene transfer in the dynamic ecological environment of dairy fermentations.}, number={3}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Madsen, SM and Mills, D and Djordjevic, G and Israelsen, H and Klaenhammer, TR}, year={2001}, month={Mar}, pages={1128–1139} }
 @article{mills_phister_dunny_mckay_1998, title={An origin of transfer (oriT) on the conjugative element pRS01 from Lactococcus lactis subsp. lactis ML3}, volume={64}, number={4}, journal={Applied and Environmental Microbiology}, author={Mills, D. A. and Phister, T. G. and Dunny, G. M. and McKay, L. L.}, year={1998}, pages={1541–1544} }