The HIV-1 protein Rev controls a critical step in viral replication by mediating the nuclear export of unspliced and singly-spliced viral mRNAs. Multiple Rev subunits assemble on the Rev Response Element (RRE), a structured region present in these RNAs, and direct their export through the Crm1 pathway. Rev-RRE assembly occurs via several Rev oligomerization and RNA-binding steps, but how these steps are coordinated to form an export–competent complex is unclear. Here, we report the first crystal structure of a Rev dimer-RRE complex, revealing a dramatic rearrangement of the Rev-dimer upon RRE binding through re-packing of its hydrophobic protein–protein interface. Rev-RNA recognition relies on sequence-specific contacts at the well-characterized IIB site and local RNA architecture at the second site. The structure supports a model in which the RRE utilizes the inherent plasticity of Rev subunit interfaces to guide the formation of a functional complex.DOI: http://dx.doi.org/10.7554/eLife.04120.001

14Mater Misericordiae Hospitals, South Brisbane, Australia B cell chronic lymphocytic leukaemia (CLL) shows evidence of familial aggregation, but the inherited basis is poorly understood. Mutations in the ATM gene have been demonstrated in CLL. This, coupled with a possibly increased risk of leukaemia in relatives of patients with Ataxia Telangiectasia, led us to question whether the ATM gene is involved in familial cases of CLL. To examine this proposition we typed five markers on chromosome 11q in 24 CLL families. No evidence for linkage between CLL and ATM in the 24 families studied and the best estimates of the proportion of sibling pairs that share no, one or both haplotypes at ATM were not different from their null expectations. This would imply that ATM is unlikely to make a significant contribution to the three-fold increase in risk of CLL seen in relatives of patients.

Chronic lymphocytic leukaemia (CLL) is a B-cell disorder, which has a median survival of over 10 years from diagnosis for stage A disease. The natural history of stage A disease is generally indolent or only slowly progressive. It is less well known that CLL may undergo spontaneous regression. We report a series of 10 such cases (eight stage A and two stage B) followed at our institutions.

Prolonged eosinophilia of unknown cause has generally been described as the hypereosinophilic syndrome, and is characterised by peripheral blood and bone marrow infiltration and frequent multisystem disease. The nature of this disorder has been questioned, and the clinical features are quite variable, suggesting its heterogeneity and probable neoplastic aetiology.A patient with severe eosinophilia, karyotype abnormalities, serum gammopathy and massive organ disease is reported. The clinical course was aggressive despite cytoreduction of eosinophils and terminated in multisystem failure.These findings are consistent with a diagnosis of eosinophilic leukaemia, and it is suggested that chromosome and cell culture studies might be useful in the early diagnosis of this controversial entity. (J Clin Pathol 1993;48:672-673)

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