Midwakh smoking as an emerging risky behavior: insight from Qatar 2022.

BACKGROUND: Alternative tobacco products like midwakh are gaining popularity as potential substitutes for traditional cigarettes despite a misconception among smokers that they may be less harmful. OBJECTIVES: To determine the prevalence, knowledge, beliefs, and predictors of midwakh smoking among adult smokers in Qatar during 2022. METHOD: An analytic cross-sectional study was conducted from January 2022 to July 2022. A simple random sample (N = 1036) was employed to include participants from the list of adults 18 years and above obtained from Qatar's National Health Information System who were invited to participate in a telephone survey. RESULTS: Among the 806 participants (response rate 77.8%), 9.3% were current midwakh smokers, and 5.2% had ever smoked midwakh. The majority were male (97.2%), non-Qatari (70.9%), and aged over 24 years. Additionally, 66.7% of midwakh smokers reported having at least one family member or friend who smoked any tobacco product. Reasons for midwakh use included enjoyment, experimentation, cessation of other tobacco products, affordability, and lack of odor. Moreover, 70.9% believed midwakh smoking could lead to addiction, while 66.7% perceived it as more dangerous than other tobacco products, potentially causing severe health conditions like lung cancer. Multivariable logistic regression indicated a significant association between midwakh use and nationality, with Qataris being 0.21 times less likely to smoke midwakh than non-Qataris (adjusted odds ratio of 0.214, 95% confidence interval: 1.58-4.225, p value of 0.0001). CONCLUSION: Midwakh smoking poses health risks comparable to other tobacco products, with peer influence being significant. Urgent action is needed to heighten awareness and allocate resources for effective intervention.

Structures of the Plasmodium falciparum heat-shock protein 70-x ATPase domain in complex with chemical fragments identify conserved and unique binding sites.

Plasmodium falciparum invades erythrocytes and extensively modifies them in a manner that increases the virulence of this malaria parasite. A single heat-shock 70 kDa-type chaperone, PfHsp70-x, is among the parasite proteins exported to the host cell. PfHsp70-x assists in the formation of a key protein complex that underpins parasite virulence and supports parasite growth during febrile episodes. Previous work resolved the crystallographic structures of the PfHsp70-x ATPase and substrate-binding domains, and showed them to be highly similar to those of their human counterparts. Here, 233 chemical fragments were screened for binding to the PfHsp70-x ATPase domain, resulting in three crystallographic structures of this domain in complex with ligands. Two binding sites were identified, with most ligands binding proximal to the ATPase nucleotide-binding pocket. Although amino acids participating in direct ligand interactions are conserved between the parasite and human erythrocytic chaperones, one nonconserved residue is also present near the ligand. This work suggests that PfHsp70-x features binding sites that may be exploitable by small-molecule ligands towards the specific inhibition of the parasite chaperone.

Experimental phasing with vanadium and application to nucleotide-binding membrane proteins.

The structure determination of soluble and membrane proteins can be hindered by the crystallographic phase problem, especially in the absence of a suitable homologous structure. Experimental phasing is the method of choice for novel structures; however, it often requires heavy-atom derivatization, which can be difficult and time-consuming. Here, a novel and rapid method to obtain experimental phases for protein structure determination by vanadium phasing is reported. Vanadate is a transition-state mimic of phosphoryl-transfer reactions and it has the advantage of binding specifically to the active site of numerous enzymes catalyzing this reaction. The applicability of vanadium phasing has been validated by determining the structures of three different protein-vanadium complexes, two of which are integral membrane proteins: the rabbit sarcoplasmic reticulum Ca2+-ATPase, the antibacterial peptide ATP-binding cassette transporter McjD from Escherichia coli and the soluble enzyme RNAse A from Bos taurus. Vanadium phasing was successful even at low resolution and despite severe anisotropy in the data. This method is principally applicable to a large number of proteins, representing six of the seven Enzyme Commission classes. It relies exclusively on the specific chemistry of the protein and it does not require any modifications, making it a very powerful addition to the phasing toolkit. In addition to the phasing power of this technique, the protein-vanadium complexes also provide detailed insights into the reaction mechanisms of the studied proteins.

Mip6 binds directly to the Mex67 UBA domain to maintain low levels of Msn2/4 stress-dependent mRNAs.

RNA-binding proteins (RBPs) participate in all steps of gene expression, underscoring their potential as regulators of RNA homeostasis. We structurally and functionally characterize Mip6, a four-RNA recognition motif (RRM)-containing RBP, as a functional and physical interactor of the export factor Mex67. Mip6-RRM4 directly interacts with the ubiquitin-associated (UBA) domain of Mex67 through a loop containing tryptophan 442. Mip6 shuttles between the nucleus and the cytoplasm in a Mex67-dependent manner and concentrates in cytoplasmic foci under stress. Photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation experiments show preferential binding of Mip6 to mRNAs regulated by the stress-response Msn2/4 transcription factors. Consistent with this binding, MIP6 deletion affects their export and expression levels. Additionally, Mip6 interacts physically and/or functionally with proteins with a role in mRNA metabolism and transcription such as Rrp6, Xrn1, Sgf73, and Rpb1. These results reveal a novel role for Mip6 in the homeostasis of Msn2/4-dependent transcripts through its direct interaction with the Mex67 UBA domain.