Successful lung transplant in a child with cystic fibrosis and persistent Blastobotrys rhaffinosifermentans infection.

Fungal respiratory infections in patients with CF are a significant concern both pre- and post-lung transplantation (LTx). Fungal infection is associated with increased mortality post-LTx, and in the past decade, the prevalence of fungal colonization in Canadian pediatric patients with CF has increased. The emergence of novel fungal pathogens is particularly challenging to the transplant community, as little is known regarding their virulence and optimal management. We present a case of a successful double-lung transplant in a pediatric patient with CF who was infected pretransplantation with a novel yeast, Blastobotrys rhaffinosifermentans. This patient was treated successfully with aggressive antifungal therapy post-transplantation, followed by extended fungal prophylaxis. The significance of fungal colonization and infection in children with CF pre- and post-LTx is reviewed.

The contribution of the budding yeast histone H2A C-terminal tail to DNA-damage responses.

The cellular response to DNA damage involves extensive interaction with and manipulation of chromatin. This includes the detection and repair of the DNA lesion, but there are also transcriptional responses to DNA damage, involving the up- or down-regulation of numerous genes. Therefore changes to chromatin structure, including covalent modification of histone proteins, are known to occur during DNA-damage responses. One of the most well characterized DNA-damage-responsive chromatin modification events is the phosphorylation of the SQ motif found in the C-terminal tail of histone H2A or the H2AX variant in higher eukaryotes. In the budding yeast, a number of additional residues in this region of histone H2A that contribute to the cellular response to DNA damage have been identified, providing an insight into the nature and complexity of the DNA-damage histone code.

A DNA translocation motif in the bacterial transcription--repair coupling factor, Mfd.

The bacterial transcription-repair coupling factor, Mfd, is a superfamily II helicase that releases transcription elongation complexes stalled by DNA damage or other obstacles. Transcription complex displacement is an ATP-dependent reaction that is thought to involve DNA translocation without the strand separation associated with classical helicase activity. We have identified single amino acid substitutions within Mfd that disrupt the ability of Mfd to displace RNA polymerase but do not prevent ATP hydrolysis or binding to DNA. These substitutions, or deletion of the C-terminal 209 residues of Mfd, abrogate the ability of Mfd to increase the efficiency of roadblock repression in vivo. The substitutions fall in a region of Mfd that is homologous to the 'TRG' motif of RecG, a protein that catalyses ATP-dependent translocation of Holliday junctions. Our results define a translocation motif in Mfd and suggest that Mfd and RecG couple ATP hydrolysis to translocation of DNA in a similar manner.