Unhealthy Lifestyle Behaviours and Psychological Distress: A Longitudinal Study of Australian Adults Aged 45 Years and Older.

Individual associations between lifestyle behaviours and mental health have been established; however, evidence on the clustering of these behaviours and the subsequent impact on mental health is limited. The purpose of this study was to examine cross-sectional and longitudinal associations between combined unhealthy lifestyle behaviours (physical activity, sitting time, sleep duration, processed meat consumption, vegetable consumption, fruit consumption, smoking status, alcohol consumption) and the development of psychological distress (measured using the Kessler Psychological Distress Scale) in a large Australian sample. Participants were 163,707 Australian adults from the 45 and Up Study. Data from baseline (2006-2009) and follow-up wave 1 (2012) were analysed using binary logistic regression. The odds of reporting high or very high psychological distress at follow-up were significantly higher for those reporting five (AOR = 2.36; 95% CI 1.41-3.97, p = 0.001) or six or more (AOR = 3.04; 95% CI 1.62-5.69, p = 0.001) unhealthy lifestyle behaviours, in comparison to those reporting no unhealthy lifestyle behaviours at baseline. These findings suggest that a holistic, multi-faceted lifestyle approach addressing multiple behaviours may be required to support and promote positive mental health and to reduce the likelihood of psychological distress.

The RxLR Motif of the Host Targeting Effector AVR3a of Phytophthora infestans Is Cleaved before Secretion.

When plant-pathogenic oomycetes infect their hosts, they employ a large arsenal of effector proteins to establish a successful infection. Some effector proteins are secreted and are destined to be translocated and function inside host cells. The largest group of translocated proteins from oomycetes is the RxLR effectors, defined by their conserved N-terminal Arg-Xaa-Leu-Arg (RxLR) motif. However, the precise role of this motif in the host cell translocation process is unclear. Here, detailed biochemical studies of the RxLR effector AVR3a from the potato pathogen Phytophthora infestans are presented. Mass spectrometric analysis revealed that the RxLR sequence of native AVR3a is cleaved off prior to secretion by the pathogen and the N terminus of the mature effector was found likely to be acetylated. High-resolution NMR structure analysis of AVR3a indicates that the RxLR motif is well accessible to potential processing enzymes. Processing and modification of AVR3a is to some extent similar to events occurring with the export element (PEXEL) found in malaria effector proteins from Plasmodium falciparum These findings imply a role for the RxLR motif in the secretion of AVR3a by the pathogen, rather than a direct role in the host cell entry process itself.

Avirulence protein 3a (AVR3a) from the potato pathogen Phytophthora infestans forms homodimers through its predicted translocation region and does not specifically bind phospholipids.

The mechanism of translocation of RxLR effectors from plant pathogenic oomycetes into the cytoplasm of their host is currently the object of intense research activity and debate. Here, we report the biochemical and thermodynamic characterization of the Phytophthora infestans effector AVR3a in vitro. We show that the amino acids surrounding the RxLR leader mediate homodimerization of the protein. Dimerization was considerably attenuated by a localized mutation within the RxLR motif that was previously described to prevent translocation of the protein into host. Importantly, we confirm that the reported phospholipid-binding properties of AVR3a are mediated by its C-terminal effector domain, not its RxLR leader. However, we show that the observed phospholipid interaction is attributable to a weak association with denatured protein molecules and is therefore most likely physiologically irrelevant.