Seek: research magazine for Kansas State University. [Introductory matter] Spring 2021

Introductory material for the Spring 2021 issue of Seek, including the table of contents and a letter from Interim Vice President for Research Beth Montelone

Inactivation of the HR6B ubiquitin-conjugating DNA repair enzyme in mice causes male sterility associated with chromatin modification.

The ubiquitin-conjugating yeast enzyme RAD6 and its human homologs hHR6A and hHR6B are implicated in postreplication repair and damage-induced mutagenesis. The yeast protein is also required for sporulation and may modulate chromatin structure via histone ubiquitination. We report the phenotype of the first animal mutant in the ubiquitin pathway: inactivation of the hHR6B-homologous gene in mice causes male infertility. Derailment of spermatogenesis becomes overt during the postmeiotic condensation of chromatin in spermatids. These findings provide a parallel between yeast sporulation and mammalian spermatogenesis and strongly implicate hHR6-dependent ubiquitination in chromatin remodeling. Since heterozygous male mice and even knockout female mice are completely normal and fertile and thus able to transmit the defect, similar hHR6B mutations may cause male infertilit

TFIIH: a key component in multiple DNA transactions

The transcription factor TFIIH is a versatile, multi-functional protein complex with multiple engagements. Apart from its role in basal transcription, TFIIH is intimately implicated in DNA repair and (probably) in cell cycle control (both of which are required to prevent carcinogenesis) as well as having possible roles in other processes. Thus, it is a striking example of the efficient use of one component for many purposes. Ingeniously, the incorporation of this essential factor into important, but non-essential, mechanisms, such as DNA repair, protects against cancer. The critical role of TFIIH in transcription function renders inactivating TFIIH mutations lethal to cells. Without this transcription connection, such mutations would lead to genetic instability and oncogenesis

Infectious disease research and one health education programs

One Health refers to the interconnected nature of the health and well-being of people, animals and the environments that they share. Central to this idea, is the realization that adverse health-effects in one area are linked to adverse effects in other area. Therefore, sustainable human health is intimately linked with sustainable animal and environmental health. This panel will include discussions of important and emerging aspects of One Health by experts in this field, each with specializations in different, but complementary, aspects of One Health that covers a wide range of disciplines and areas of expertise

The rem Mutations in the ATP-Binding Groove of the Rad3/XPD Helicase Lead to Xeroderma pigmentosum-Cockayne Syndrome-Like Phenotypes

The eukaryotic TFIIH complex is involved in Nucleotide Excision Repair and transcription initiation. We analyzed three yeast mutations of the Rad3/XPD helicase of TFIIH known as rem (recombination and mutation phenotypes). We found that, in these mutants, incomplete NER reactions lead to replication fork breaking and the subsequent engagement of the homologous recombination machinery to restore them. Nevertheless, the penetrance varies among mutants, giving rise to a phenotype gradient. Interestingly, the mutations analyzed reside at the ATP-binding groove of Rad3 and in vivo experiments reveal a gain of DNA affinity upon damage of the mutant Rad3 proteins. Since mutations at the ATP-binding groove of XPD in humans are present in the Xeroderma pigmentosum-Cockayne Syndrome (XP-CS), we recreated rem mutations in human cells, and found that these are XP-CS-like. We propose that the balance between the loss of helicase activity and the gain of DNA affinity controls the capacity of TFIIH to open DNA during NER, and its persistence at both DNA lesions and promoters. This conditions NER efficiency and transcription resumption after damage, which in human cells would explain the XP-CS phenotype, opening new perspectives to understand the molecular basis of the role of XPD in human disease.Research was funded by grants from the Spanish Ministry of Economy and Competitiveness (BFU2010-16372), the Junta de Andalucía (CVI4567) and the European Union (FEDER).Peer reviewe