Characterizing phenotypic diversity of trehalose biosynthesis mutants in multiple wild strains of Saccharomyces cerevisiae

In the yeast Saccharomyces cerevisiae, trehalose-6-phospahte synthase (Tps1) and trehalose-6-phosphate phosphatase (Tps2) are the main proteins catalyzing intracellular trehalose production. In addition to Tps1 and Tps2, 2 putative regulatory proteins with less clearly defined roles also appear to be involved with trehalose production, Tps3 and Tsl1. While this pathway has been extensively studied in laboratory strains of S. cerevisiae, we sought to examine the phenotypic consequences of disrupting these genes in wild strains. Here we deleted the TPS1, TPS2, TPS3, and TSL1 genes in 4 wild strains and 1 laboratory strain for comparison. Although some tested phenotypes were not shared between all strains, deletion of TPS1 abolished intracellular trehalose, caused inability to grow on fermentable carbon sources and resulted in severe sporulation deficiency for all 5 strains. After examining tps1 mutant strains expressing catalytically inactive variants of Tps1, our results indicate that Tps1, independent of trehalose production, is a key component for yeast survival in response to heat stress, for regulating sporulation, and growth on fermentable sugars. All tps2Δ mutants exhibited growth impairment on nonfermentable carbon sources, whereas variations were observed in trehalose synthesis, thermosensitivity and sporulation efficiency. tps3Δ and tsl1Δ mutants exhibited mild or no phenotypic disparity from their isogenic wild type although double mutants tps3Δ tsl1Δ decreased the amount of intracellular trehalose production in all 5 strains by 17-45%. Altogether, we evaluated, confirmed, and expanded the phenotypic characteristics associated trehalose biosynthesis mutants. We also identified natural phenotypic variants in multiple strains that could be used to genetically dissect the basis of these traits and then develop mechanistic models connecting trehalose metabolism to diverse cellular processes.

Trehalose and its applications in the food industry

Trehalose is a nonreducing disaccharide composed of two glucose molecules linked by α, α-1,1-glycosidic bond. It is present in a wide variety of organisms, including bacteria, fungi, insects, plants, and invertebrate animals. Trehalose has distinct physical and chemical properties that have been investigated for their biological importance in a range of prokaryotic and eukaryotic species. Emerging research on trehalose has identified untapped opportunities for its application in the food, medical, pharmaceutical, and cosmetics industries. This review summarizes the chemical and biological properties of trehalose, its occurrence and metabolism in living organisms, its protective role in molecule stabilization, and natural and commercial production methods. Utilization of trehalose in the food industry, in particular how it stabilizes protein, fat, carbohydrate, and volatile compounds, is also discussed in depth. Challenges and opportunities of its application in specific applications (e.g., diagnostics, bioprocessing, ingredient technology) are described. We conclude with a discussion on the potential of leveraging the unique molecular properties of trehalose in molecular stabilization for improving the safety, quality, and sustainability of our food systems.

Trehalose and tardigrade CAHS proteins work synergistically to promote desiccation tolerance

Tardigrades are microscopic animals renowned for their ability to survive extreme desiccation. Unlike many desiccation-tolerant organisms that accumulate high levels of the disaccharide trehalose to protect themselves during drying, tardigrades accumulate little or undetectable levels. Using comparative metabolomics, we find that despite being enriched at low levels, trehalose is a key biomarker distinguishing hydration states of tardigrades. In vitro, naturally occurring stoichiometries of trehalose and CAHS proteins, intrinsically disordered proteins with known protective capabilities, were found to produce synergistic protective effects during desiccation. In vivo, this synergistic interaction is required for robust CAHS-mediated protection. This demonstrates that trehalose acts not only as a protectant, but also as a synergistic cosolute. Beyond desiccation tolerance, our study provides insights into how the solution environment tunes intrinsically disordered proteins’ functions, many of which are vital in biological contexts such as development and disease that are concomitant with large changes in intracellular chemistry.

The disaccharide trehalose is a synergistic cosolute and key biomarker of desiccation tolerance in tardigrades.

Desiccation tolerance: an unusual window into stress biology

Climate change has accentuated the importance of understanding how organisms respond to stresses imposed by changes to their environment, like water availability. Unusual organisms, called anhydrobiotes, can survive loss of almost all intracellular water. Desiccation tolerance of anhydrobiotes provides an unusual window to study the stresses and stress response imposed by water loss. Because of the myriad of stresses that could be induced by water loss, desiccation tolerance seemed likely to require many established stress effectors. The sugar trehalose and hydrophilins (small intrinsically disordered proteins) had also been proposed as stress effectors against desiccation because they were found in nearly all anhydrobiotes, and could mitigate desiccation-induced damage to model proteins and membranes in vitro. Here, we summarize in vivo studies of desiccation tolerance in worms, yeast, and tardigrades. These studies demonstrate the remarkable potency of trehalose and a subset of hydrophilins as the major stress effectors of desiccation tolerance. They act, at least in part, by limiting in vivo protein aggregation and loss of membrane integrity. The apparent specialization of individual hydrophilins for desiccation tolerance suggests that other hydrophilins may have distinct roles in mitigating additional cellular stresses, thereby defining a potentially new functionally diverse set of stress effectors.

Synergy between the small intrinsically disordered protein Hsp12 and trehalose sustain viability after severe desiccation

Anhydrobiotes are rare microbes, plants and animals that tolerate severe water loss. Understanding the molecular basis for their desiccation tolerance may provide novel insights into stress biology and critical tools for engineering drought-tolerant crops. Using the anhydrobiote, budding yeast, we show that trehalose and Hsp12, a small intrinsically disordered protein (sIDP) of the hydrophilin family, synergize to mitigate completely the inviability caused by the lethal stresses of desiccation. We show that these two molecules help to stabilize the activity and prevent aggregation of model proteins both in vivo and in vitro. We also identify a novel in vitro role for Hsp12 as a membrane remodeler, a protective feature not shared by another yeast hydrophilin, suggesting that sIDPs have distinct biological functions.

Tardigrades Use Intrinsically Disordered Proteins to Survive Desiccation

Tardigrades are microscopic animals that survive a remarkable array of stresses, including desiccation. How tardigrades survive desiccation has remained a mystery for more than 250 years. Trehalose, a disaccharide essential for several organisms to survive drying, is detected at low levels or not at all in some tardigrade species, indicating that tardigrades possess potentially novel mechanisms for surviving desiccation. Here we show that tardigrade-specific intrinsically disordered proteins (TDPs) are essential for desiccation tolerance. TDP genes are constitutively expressed at high levels or induced during desiccation in multiple tardigrade species. TDPs are required for tardigrade desiccation tolerance, and these genes are sufficient to increase desiccation tolerance when expressed in heterologous systems. TDPs form non-crystalline amorphous solids (vitrify) upon desiccation, and this vitrified state mirrors their protective capabilities. Our study identifies TDPs as functional mediators of tardigrade desiccation tolerance, expanding our knowledge of the roles and diversity of disordered proteins involved in stress tolerance.

Trehalose is a versatile and long-lived chaperone for desiccation tolerance

BACKGROUND

Diverse organisms across taxa are desiccation tolerant, capable of surviving extreme water loss. Remarkably, desiccation tolerant organisms can survive years without water. However, the molecular mechanisms underlying this rare trait are poorly understood.

RESULTS

Here, using Saccharomyces cerevisiae, we show that intracellular trehalose is essential for survival to long-term desiccation. The time frame for maintaining long-term desiccation tolerance consists of a balance of trehalose stockpiled prior to desiccation and trehalose degradation by trehalases in desiccated cells. The activity of trehalases in desiccated cell reveals the stunning ability of cells to retain enzymatic activity while desiccated. Interestingly, the protein chaperone Hsp104 compensates for loss of trehalose during short-term, but not long-term, desiccation. We show that desiccation induces protein misfolding/aggregation of cytoplasmic and membrane proteins using luciferase and prion reporters. We demonstrate that trehalose, but not Hsp104, mitigates the aggregation of both cytoplasmic and membrane prions. We propose that desiccated cells initially accumulate both protein and chemical chaperones, like Hsp104 and trehalose, respectively. As desiccation extends, the activities of the protein chaperones are lost because of their complexity and requirement for energy, leaving trehalose as the major protector against the aggregation of cytoplasmic and membrane proteins.

CONCLUSIONS

Our results suggest that trehalose is both a more stable and more versatile protectant than protein chaperones, explaining its important role in desiccation tolerance and emphasizing the translational potential of small chemical chaperones as stress effectors.

The relationship between etiology, symptom severity and indications of surgery in cases of anal incontinence: a 25-year analysis of 1,046 patients at a tertiary coloproctology practice

BACKGROUND

The etiology of anal incontinence (AI) is often multifactorial. There is little data on the relationship between the etiology of AI, symptom severity, and the need for surgery. The aim of our study was to investigate this association in a large number of unselected patients with AI referred to a tertiary specialist coloproctological practice.

METHODS

Patients with AI seen at our unit between 1983 and 2008 were analyzed. The main etiologies were categorized as congenital, traumatic, neurologic, idiopathic, post-operative, post-obstetric, secondary to rectal prolapse, or inflammatory bowel disease. The severity of AI was graded using the validated Pescatori incontinence scale.

RESULTS

Overall, 1,046 patients were studied. The AI score was higher in patients with congenital (4.7 ± 1.1), traumatic (4.6 ± 1.4), and neurological (4.4 ± 1.2) incontinence. Surgical treatment was indicated in 214 cases (20.5%). Patients with AI related to trauma and congenital anomalies required surgery in 43.5 and 31.4% of cases, respectively, a percentage significantly higher than that for patients with other etiologies (P = 0.002). Prolapse-related AI usually responded to correction of the prolapse.

CONCLUSIONS

Patients with congenital, traumatic, and neurological AI tend to have greater symptom severity. Traumatic, rectal prolapse-related, and congenital AI cases more often require surgery.

Colonic cavernous hemangiomas: a report of two cases treated by laparoscopic surgery

Hemangiomas are rare vascular tumors. They most commonly appear in the small bowel, as well as the colon and the rectum. Here, we report two cases of male patients who were admitted to our hospital for low rectal painless bleeding, misdiagnosed of hemorrhoid bleeding. Colonoscopy reported vascular tumors in both cases, which we surgically removed.

[Synchronous diverticulitis: a case report.]

Diverticular colonic disease is not as common in developing nations as in western and industrialized societies, accounting for approximately 130 000 hospitalizations per year in the United States, being diverticulitis the most frequent complication. Synchronous presentation of this complication is very rare, with only one case reported in literature. We present a patient who presented with diffuse abdominal pain. Colonoscopy was performed identifying a mass in the sigmoid colon and a perforation in the cecum. Patient underwent total abdominal colectomy with ileorectal anastomosis and protective loop ileostomy. Histopathologic examination revealed synchronous complicated diverticular disease of the sigmoid and cecum. In this report we disclose this type of atypical presentation of diverticular disease and establish that the approach taken is safe and feasible.

Hsp90 nuclear accumulation in quiescence is linked to chaperone function and spore development in yeast

The protein chaperone Hsp90 and its co-chaperone Sba1/p23 are found to accumulate in the nucleus of haploid yeast cells as glucose is exhausted and in sporulating diploids. Novel and existing Hsp90 mutants exhibit defects in nuclear translocation and spore development, linking these two phenomena.

The 90-kDa heat-shock protein (Hsp90) operates in the context of a multichaperone complex to promote maturation of nuclear and cytoplasmic clients. We have discovered that Hsp90 and the cochaperone Sba1/p23 accumulate in the nucleus of quiescent Saccharomyces cerevisiae cells. Hsp90 nuclear accumulation was unaffected in sba1Δ cells, demonstrating that Hsp82 translocates independently of Sba1. Translocation of both chaperones was dependent on the α/β importin SRP1/KAP95. Hsp90 nuclear retention was coincident with glucose exhaustion and seems to be a starvation-specific response, as heat shock or 10% ethanol stress failed to elicit translocation. We generated nuclear accumulation-defective HSP82 mutants to probe the nature of this targeting event and identified a mutant with a single amino acid substitution (I578F) sufficient to retain Hsp90 in the cytoplasm in quiescent cells. Diploid hsp82-I578F cells exhibited pronounced defects in spore wall construction and maturation, resulting in catastrophic sporulation. The mislocalization and sporulation phenotypes were shared by another previously identified HSP82 mutant allele. Pharmacological inhibition of Hsp90 with macbecin in sporulating diploid cells also blocked spore formation, underscoring the importance of this chaperone in this developmental program.

[Pancreatic-duodenectomy for invasive colon cancer in a patient with Lynch syndrome. Case report.]

Despite the screening efforts in the general population and particularly in families with hereditary colon cancer, locally advanced colon cancer remains a common clinical problem. In block resection is considered mainstay therapy in these patients. The aim of this report is to present a case of right-sided colon cancer with a medullar phenotype invading the duodenum treated through in block resection. A case of a 54-year-old male with a family history of colon and pancreatic cancer with lower gastrointestinal tract bleeding is presented. Colonoscopy and computed tomography scan showed a tumor in the colonic hepatic flexure invading the duodenum. The patient underwent an in block resection of the right colon, duodenum, pancreas and antrum. The histopathological study showed a T4N0M0 adenocarcinoma invading the duodenum, pancreas and antrum with negative margins. His postoperative evolution was complicated with a pancreatic fistula, which resolved with conservative measures. In conclusion, in block resection is the treatment of choice for locally advanced colon cancer with invasion to duodenum and pancreas and should be performed in high-volume centers familiar with this type of procedures. Key words: pancreaticoduodenectomy, colon cancer, Lynch syndrome, pancreas, surgery, Mexico.