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Protein engineering often targets binding pockets or active sites which are enriched in epistasis--nonadditive interactions between amino acid substitutions--and where the combined effects of multiple single substitutions are difficult to predict. Few existing sequence-fitness datasets capture epistasis at large scale, especially for enzyme catalysis, limiting the development and assessment of model-guided enzyme engineering approaches. We present here a combinatorially complete, 160,000-variant fitness landscape across four residues in the active site of an enzyme. Assaying the native reaction of a thermostable ß-subunit of tryptophan synthase (TrpB) in a nonnative environment yielded a landscape characterized by significant epistasis and many local optima. These effects prevent simulated directed evolution approaches from efficiently reaching the global optimum. There is nonetheless wide variability in the effectiveness of different directed evolution approaches, which together provide experimental benchmarks for computational and machine learning workflows. The most-fit TrpB variants contain a substitution that is nearly absent in natural TrpB sequences--a result that conservation-based predictions would not capture. Thus, although fitness prediction using evolutionary data can enrich in more-active variants, these approaches struggle to identify and differentiate among the most-active variants, even for this near-native function. Overall, this work presents a large-scale testing ground for model-guided enzyme engineering and suggests that efficient navigation of epistatic fitness landscapes can be improved by advances in both machine learning and physical modeling. [ABSTRACT FROM AUTHOR]

Animals sense and respond to nutrient availability in their environments, a task coordinated in part by the mTOR complex 1 (mTORC1) pathway. mTORC1 regulates growth in response to nutrients and, in mammals, senses specific amino acids through specialized sensors that bind the GATOR1/2 signaling hub. Given that animals can occupy diverse niches, we hypothesized that the pathway might evolve distinct sensors in different metazoan phyla. Whether such customization occurs, and how the mTORC1 pathway might capture new inputs, is unknown. Here, we identify the Drosophila melanogaster protein Unmet expectations (CG11596) as a species-restricted methionine sensor that directly binds the fly GATOR2 complex in a fashion antagonized by S-adenosylmethionine (SAM). We find that in Dipterans GATOR2 rapidly evolved the capacity to bind Unmet and to thereby repurpose a previously independent methyltransferase as a SAM sensor. Thus, the modular architecture of the mTORC1 pathway allows it to co-opt preexisting enzymes to expand its nutrient sensing capabilities, revealing a mechanism for conferring evolvability on an otherwise conserved system.Unmet expectations, a previously uncharacterized fly protein, is a SAM sensor for the mTORC1 pathway. Tracing the evolution of Unmet reveals that the pathway uses the GATOR2 complex to capture and repurpose ancestral enzymes as nutrient sensors. [ABSTRACT FROM AUTHOR]

Problem/condition: In 2021, approximately 75,000 persons died of violence-related injuries in the United States. This report summarizes data from CDC's National Violent Death Reporting System (NVDRS) on violent deaths that occurred in 48 states, the District of Columbia, and Puerto Rico in 2021. Results are reported by sex, age group, race and ethnicity, method of injury, type of location where the injury occurred, circumstances of injury, and other selected characteristics. This report introduces additional incident and circumstance variables, which now include child victim-specific circumstance information. This report also incorporates new U.S. Census Bureau race and ethnicity categories, which now account for more than one race and Native Hawaiian or other Pacific Islander categories and include updated denominators to calculate rates for these populations., Period Covered: 2021., Description of System: NVDRS collects data regarding violent deaths from death certificates, coroner and medical examiner records, and law enforcement reports. This report includes data collected for violent deaths that occurred in 2021. Data were collected from 48 states (all states with exception of Florida and Hawaii), the District of Columbia, and Puerto Rico. Forty-six states had statewide data, two additional states had data from counties representing a subset of their population (31 California counties, representing 64% of its population, and 13 Texas counties, representing 63% of its population), and the District of Columbia and Puerto Rico had jurisdiction-wide data. NVDRS collates information for each violent death and links deaths that are related (e.g., multiple homicides, homicide followed by suicide, or multiple suicides) into a single incident., Results: For 2021, NVDRS collected information on 68,866 fatal incidents involving 70,688 deaths that occurred in 48 states (46 states collecting statewide data, 31 California counties, and 13 Texas counties), and the District of Columbia. The deaths captured in NVDRS accounted for 86.5% of all homicides, legal intervention deaths, suicides, unintentional firearm injury deaths, and deaths of undetermined intent in the United States in 2021. In addition, information was collected for 816 fatal incidents involving 880 deaths in Puerto Rico. Data for Puerto Rico were analyzed separately. Of the 70,688 deaths, the majority (58.2%) were suicides, followed by homicides (31.5%), deaths of undetermined intent that might be due to violence (8.2%), legal intervention deaths (1.3%) (i.e., deaths caused by law enforcement and other persons with legal authority to use deadly force acting in the line of duty, excluding legal executions), and unintentional firearm injury deaths (<1.0%). The term "legal intervention" is a classification incorporated into the International Classification of Diseases, Tenth Revision, and does not denote the lawfulness or legality of the circumstances surrounding a death caused by law enforcement.Demographic patterns and circumstances varied by manner of death. The suicide rate was higher for males than for females. Across all age groups, the suicide rate was highest among adults aged ≥85 years. In addition, non-Hispanic American Indian or Alaska Native (AI/AN) persons had the highest suicide rates among all racial and ethnic groups. Among both males and females, the most common method of injury for suicide was a firearm. Among all suicide victims, when circumstances were known (84.4%), suicide was most often preceded by a mental health, intimate partner, or physical health problem or by a recent or impending crisis during the previous or upcoming 2 weeks. The homicide rate was higher for males than for females. Among all homicide victims, the homicide rate was highest among persons aged 20-24 years compared with other age groups. Non-Hispanic Black or African American (Black) males experienced the highest homicide rate of any racial or ethnic group. Among all homicide victims, the most common method of injury was a firearm. When the relationship between a homicide victim and a suspect was known, the suspect was most frequently an acquaintance or friend for male victims and a current or former intimate partner for female victims. Homicide most often was precipitated by an argument or conflict, occurred in conjunction with another crime, or, for female victims, was related to intimate partner violence. Nearly all victims of legal intervention deaths were male, and the legal intervention death rate was highest among men aged 30-34 years. The legal intervention death rate was highest among AI/AN males, followed by Black males. A firearm was used in the majority of legal intervention deaths. When circumstances were known, the most frequent circumstances reported for legal intervention deaths were as follows: the victim used a weapon in the incident and the victim had a substance use problem (other than alcohol use). Other causes of death included unintentional firearm injury deaths and deaths of undetermined intent. Unintentional firearm injury deaths were most frequently experienced by males, non-Hispanic White (White) persons, and persons aged 15-24 years. These deaths most frequently occurred while the shooter was playing with a firearm and were precipitated by a person unintentionally pulling the trigger. The rate of deaths of undetermined intent was highest among males, particularly among AI/AN and Black males, and among adults aged 30-54 years. Poisoning was the most common method of injury in deaths of undetermined intent, and opioids were detected in nearly 80% of decedents tested for those substances., Interpretation: This report provides a detailed summary of data from NVDRS on violent deaths that occurred in 2021. The suicide rate was highest among AI/AN and White males, whereas the homicide rate was highest among Black males. Intimate partner violence precipitated a large proportion of homicides for females. Mental health problems, intimate partner problems, interpersonal conflicts, and acute life stressors were primary precipitating circumstances for multiple types of deaths examined., Public Health Action: Violence is preventable, and data can guide public health action. NVDRS data are used to monitor the occurrence of violence-related fatal injuries and assist public health authorities in developing, implementing, and evaluating programs, policies, and practices to reduce and prevent violent deaths. NVDRS data can be used to enhance prevention efforts into actionable strategies. States or jurisdictions have used their Violent Death Reporting System (VDRS) data to guide suicide prevention efforts and highlight where additional focus is needed. For example, North Carolina VDRS program data have played a significant role in expanding activities related to firearm safety and injury prevention. The program served as a primary data source for partners, which led to the creation of the Office of Violence Prevention in the state, focusing on combatting firearm-related deaths. In Maine, the VDRS provided data on law enforcement officer suicides that were used to help support a bill mandating mental health resiliency and awareness training in the state's law enforcement training academy, along with plans for similar training addressing mental health, substance use, and alcohol problems among corrections officers. In addition, states and jurisdictions have also used their VDRS data to examine factors related to homicide in their state or jurisdiction. For example, Georgia VDRS collaborated with the City of Atlanta Mayor's Office of Violence Reduction to develop two public dashboards that not only offer comprehensive data on violent deaths but also present data on the geographic distribution of populations disproportionately affected by violence to help inform violence prevention interventions., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.